Control system and method for electric vehicle

ABSTRACT

An electric traction vehicle is described herein which may be used to provide power to off-board electric power-consuming systems or devices. The electric traction vehicle may provide 250 kilowatts or more of three phase AC power to an off-board electric power consuming system. The electric traction vehicle may also include an electrical power storage device which can be selectively discharged to allow the vehicle to be serviced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/761,996 entitled “Control System and Method for Electric Vehicle,”filed Jun. 12, 2007, pending, which is a continuation of U.S. patentapplication Ser. No. 11/113,470, entitled “Control System and Method forElectric Vehicle,” filed on Apr. 25, 2005, issued as U.S. Pat. No.7,277,782, which is a continuation of U.S. patent application Ser. No.10/326,862, entitled “Control System for Electric Vehicle,” filed onDec. 19, 2002, issued as U.S. Pat. No. 6,885,920, which (1) is acontinuation in part of U.S. patent application Ser. No. 09/774,981,entitled “A/C Bus Assembly for Electronic Traction Vehicle,” filed onJan. 31, 2001, issued as U.S. Pat. No. 6,757,597, and (2) claimspriority under 35 U.S.C. § 119(e) to: (a) U.S. Provisional PatentApplication No. 60/388,451, entitled “Control System and Method for anEquipment Service Vehicle,” filed on Jun. 13, 2002, (b) U.S. ProvisionalPatent Application No. 60/360,479, entitled “Turret Control System andMethod for a Fire Fighting Vehicle,” filed on Feb. 28, 2002, and (c)U.S. Provisional Patent Application No. 60/342,292, entitled “VehicleControl and Monitoring System and Method,” filed on Dec. 21, 2001, allof which are expressly incorporated by reference herein in theirentireties.

This application also incorporates by reference the following documentsin their entireties: (1) U.S. patent application Ser. No. 09/927,946,entitled “Control System and Method for an Equipment Service Vehicle,”filed on Aug. 10, 2001, issued as U.S. Pat. No. 7,024,296, (2) U.S.patent application Ser. No. 09/500,506, entitled “Equipment ServiceVehicle Having On-Board Diagnostic System,” filed on Feb. 9, 2000,issued as U.S. Pat. No. 6,553,290, (3) U.S. patent application Ser. No.09/384,393, entitled “Military Vehicle Having Cooperative ControlNetwork With Distributed I/O Interfacing,” filed Aug. 27, 1999, issuedas U.S. Pat. No. 6,421,593, (4) U.S. patent application Ser. No.09/364,690, entitled “Firefighting Vehicle Having Cooperative ControlNetwork With Distributed I/O Interfacing,” filed Jul. 30, 1999,abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to electric vehicles. The presentinvention also relates to control systems and methods for electricvehicles.

An electronic traction vehicle is a vehicle that uses electricity insome form or another to provide all or part of the propulsion power ofthe vehicle. This electricity can come from a variety of sources, suchas stored energy devices relying on chemical conversions (batteries),stored electrical charge devices (capacitors), stored energy devicesrelying on mechanical stored energy (e.g. flywheels, pressureaccumulators), and energy conversion products. In a typical conventionalelectric traction vehicle, a prime mover, such as a diesel engine, isused to drive an electric generator or alternator which supplieselectric current to one or more traction motors. The traction motorstypically are coupled to wheel sets on the vehicle. A typical vehiclethat utilizes this type of electric traction is a railroad locomotive.In some conventional electric traction vehicles, stored energy is usedto provide the main power which provides the electrical current to oneor a plurality of traction motors. A typical vehicle that utilizes thistype of electric traction is a golf cart or battery powered electriccar. In some conventional electric traction vehicles, having more thanone sources of energy is desirable. By having more than one source ofenergy, some optimizations in the design can allow for more efficientpower production, thus allowing power to be used from different sourcesto come up with a more efficient system for traction. These types ofvehicles are commonly referred to as hybrid electric vehicles (HEV).Series and Parallel HEV system designs are what is usually encountered.

A master controller is often used to control the overall system and givecommand signals to the engine, generator/alternator, prime mover energyconversion (AC to DC) stored energy conversion, and/or traction levelenergy conversion (DC to AC). This controller architecture requires ahighly integrated control strategy. It also provide a single point offailure for the traction system.

Thus, there is a need for an electric traction vehicle that is modularin design and control. There is also a need for electric tractionvehicle that can be updated and upgraded as new technology andcomponents become available without a required redesign of the overallvehicle system. There is also a need for improved control systems andmethods for electric vehicles, and systems and methods for servicing,repairing and monitoring electric vehicles.

SUMMARY OF THE INVENTION

According to a first preferred embodiment, an electric traction vehiclecomprises a vehicle platform, a communication network, a power sourcemounted on the vehicle platform, a plurality of drive wheels rotatablymounted on the vehicle platform, a plurality of electric motors coupledto respective ones of the plurality of drive wheels, and a plurality ofmicroprocessor-based interface modules coupled to the plurality ofelectric motors. The interface modules are configured to control theplurality of electric motors and are coupled to each other by way of thecommunication network.

According to a second preferred embodiment, a vehicle comprises firstand second drive wheels, a power source, a power transmission link, aplurality of input devices, a plurality of output devices, acommunication network, and a plurality of microprocessor-based interfacemodules. The plurality of output devices include first and second motordrive systems which further include first and second electric motors.The first and second electric motors are respectively coupled to thefirst and second drive wheel and being capable of applying torque to thefirst and second drive wheels to drive motion of the vehicle. Theplurality of interface modules are coupled to the power source by way ofthe power transmission link and are interconnected to each other by wayof the communication network. Each of the plurality of interface modulesis coupled to respective ones of the plurality of input devices and theplurality of output devices by way of respective dedicated communicationlinks. The plurality of interface modules cooperate to control theplurality of output devices based on input status information from theplurality of input devices. At least one of the plurality of interfacemodules controls power distribution to the first and second motor drivesystems to control a speed of the vehicle.

Other objects, features, and advantages of the present invention willbecome apparent to those skilled in the art from the following detaileddescription and accompanying drawings. It should be understood, however,that the detailed description and specific examples, while indicatingpreferred embodiments of the present invention, are given by way ofillustration and not limitation. Many modifications and changes withinthe scope of the present invention may be made without departing fromthe spirit thereof, and the invention includes all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a fire truck having a control systemaccording to one embodiment of the present invention;

FIG. 2 is a block diagram of the control system of FIG. 1 showingselected aspects of the control system in greater detail;

FIG. 3. is a simplified block diagram of the control system of FIGS.1-2;

FIG. 4 is a flowchart showing the operation of the control system ofFIG. 3 to turn on an output device in response to an operator input;

FIG. 5 is a flowchart showing the operation of the control system ofFIG. 3 to turn off an output device in response to the failure of aninterlock condition;

FIG. 6 is another simplified block diagram of the control system ofFIGS. 1-2;

FIG. 7 is a flowchart showing the operation of the control system ofFIG. 6 to implement load management when battery voltage decreases;

FIG. 8 is a flowchart showing the operation of the control system ofFIG. 6 to restore power to output devices that have been shed during theload management illustrated in FIG. 7;

FIG. 9 is another simplified block diagram of the control system ofFIGS. 1-2;

FIGS. 10A-10B are flowcharts showing the operation of the control systemof FIG. 9 to implement load sequencing in response to an operator input;

FIGS. 11A-11B are flowcharts showing the operation of the control systemof FIG. 9 to implement load sequencing in different orders depending onan operating mode of the fire truck;

FIG. 12 is a schematic view of an aerial device having a control systemaccording to another embodiment of the present invention;

FIG. 13 is a more detailed block diagram of the control system of FIG.12;

FIG. 14 is a schematic view of a military vehicle having a controlsystem according to another embodiment of the present invention;

FIGS. 15-16 are block diagrams of the control system of FIG. 14 showingselected aspects of the control system in greater detail.

FIGS. 17A-17B are modified views of the block diagram of FIG. 16 showingthe operation of the control system to reconfigure itself in a failuremode of operation;

FIG. 18 is a diagram showing the memory contents of an exemplaryinterface module in greater detail;

FIG. 19 is truth table in which an output is controlled with anadditional layer of failure management for inputs with undeterminedstates;

FIG. 20 is an overview of a preferred variant vehicle system;

FIG. 21 is a block diagram of the control system of FIG. 14 showingselected aspects of the control system in greater detail;

FIG. 22 is an I/O status table of FIG. 21 shown in greater detail;

FIG. 23 is a flowchart describing the operation of the control system ofFIG. 21 in greater detail;

FIG. 24 is a data flow diagram describing data flow through an exemplaryinterface module during the process of FIG. 23;

FIG. 25 is a schematic diagram of an exemplary embodiment of an electrictraction vehicle providing an exemplary embodiment of an AC bus assemblycoupled to various modules on the vehicle;

FIG. 26 is a schematic diagram showing the vehicle of FIG. 25 being usedas a mobile electric power plant;

FIG. 27 is a schematic diagram showing selected aspects of a controlsystem of FIG. 25 in greater detail;

FIG. 28 is a flowchart showing the operation of a control system of FIG.25 in greater detail;

FIG. 29 is a schematic diagram showing auxiliary drive modules used inthe vehicle of FIG. 25;

FIG. 30 is a flowchart showing another aspect of the operation of acontrol system of FIG. 25 in greater detail;

FIG. 31A is a top plan view illustration of an exemplary embodiment of adifferential assembly coupled to an electric motor for driving at leasttwo wheels and supported by a suspension assembly.

FIG. 31B is an end view partial sectional view of an exemplaryembodiment of an electric traction vehicle support structure coupled toa suspension assembly which suspends at least one wheel relative to thevehicle support structure;

FIGS. 32A-32B is a block diagram showing various configurations forconnecting interface modules to drive controllers in the electrictraction vehicle of FIG. 25;

FIG. 33 is a schematic block diagram illustrating various entitiesconnected to the Internet for the transmission of data indicative of anelectric traction vehicle;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Patent application Ser. No. 09/384,393, filed Aug. 27, 1999, allowed,discloses various embodiments of a control system architecture inconnection with fire trucks, military vehicles and other types ofvehicles. A particularly advantageous use of the preferred controlsystem architecture is in the context of electric traction vehicles and,as described below, the vehicles disclosed in these applications may beimplemented as electric traction vehicles. For such uses, the controlsystems described in the above-mentioned applications may be used tocontrol additional output devices associated with the electric tractionvehicle such as electric motors used to drive motion of the vehicle, andto provide I/O status information which may be transmitted off-board thevehicle. For convenience, the contents of the above-mentionedapplication is repeated below, followed by a description of an electrictraction vehicle embodiment and remote monitoring applications which ina preferred embodiment use a control system of a type disclosed in theabove-mentioned applications.

A. Fire Truck Control System

1. Architecture of Preferred Fire Truck Control System

Referring now to FIG. 1, a preferred embodiment of a fire truck 10having a control system 12 is illustrated. By way of overview, thecontrol system 12 comprises a central control unit 14, a plurality ofmicroprocessor-based interface modules 20 and 30, a plurality of inputdevices 40 and a plurality of output devices 50. The central controlunit 14 and the interface modules 20 and 30 are connected to each otherby a communication network 60.

More specifically, the central control unit 14 is a microprocessor-baseddevice and includes a microprocessor 15 that executes a control program16 (see FIG. 2) stored in memory of the central control unit 14. Thecontrol program is shown and described in greater detail below inconjunction with the flowcharts of FIGS. 4, 5, 7, 8 and 10. In general,the control unit 14 executes the program to collect and store inputstatus information from the input devices 40, and to control the outputdevices 50 based on the collected status information. The controlprogram preferably implements an interlock system (e.g., FIG. 5), a loadmanager (e.g., FIGS. 7-8), and a load sequencer (e.g., FIGS. 10A-10B).As described below, the central control unit 14 is preferably notconnected to the I/O devices 40 and 50 directly but rather onlyindirectly by way of the interface modules 20 and 30, thereby enablingdistributed data collection and power distribution. The I/O devices 40and 50 are located on a chassis 11 of the fire truck 10, which includesboth the body and the underbody of the fire truck 10.

In the illustrated embodiment, two different types of interface modulesare used. The interface modules 20 interface mainly with switches andlow power indicators, such as LEDs that are integrally fabricated with aparticular switch and that are used to provide visual feedback to anoperator regarding the state of the particular switch. For this reason,the interface modules 20 are sometimes referred to herein as “SIMs”(“switch interface modules”). Herein, the reference numeral “20” is usedto refer to the interface modules 20 collectively, whereas the referencenumerals 21, 22 and 23 are used to refer to specific ones of theinterface modules 20.

The interface modules 30 interface with the remaining I/O devices 40 and50 on the vehicle that do not interface to the interface modules 20, andtherefore are sometimes referred to herein as “VIMs” (“vehicle interfacemodules”). The interface modules 30 are distinguishable from theinterface modules 20 mainly in that the interface modules 30 are capableof handling both analog and digital inputs and outputs, and in that theyare capable of providing more output power to drive devices such asgauges, valves, solenoids, vehicle lighting and so on. The analogoutputs may be true analog outputs or they may be pulse width modulationoutputs that are used to emulate analog outputs. Herein, the referencenumeral “30” is used to refer to the interface modules 30 collectively,whereas the reference numerals 31, 32, 33, 34 and 35 are used to referto specific ones of the interface modules 30.

Although two different types of interface modules are used in theillustrated embodiment, depending on the application, it may bedesirable to use only a single type of interface module in order toreduce inventory requirements. Additionally, while in FIG. 1 three ofthe interface modules 20 and five of the interface modules 30 are shown,this arrangement is again simply one example. It may be desirable toprovide each interface module with more I/O points in order to reducethe number of interface modules that are required, or to use moreinterface modules with a smaller number of I/O points in order to makethe control system 12 more highly distributed. Of course, the number ofinterface modules will also be affected by the total number of I/Opoints in the control system.

FIG. 1 shows an approximate distribution of the interface modules 20 and30 throughout the fire truck 10. In general, in order to minimizewiring, the interface modules 20 and 30 are placed so as to be locatedas closely as possible to the input devices 40 from which input statusinformation is received and the output devices 50 that are controlled.As shown in FIG. 1, there is a large concentration of interface modules20 and 30 near the front of the fire truck 10, with an additionalinterface module 34 at mid-length of the fire truck 10 and anotherinterface module 35 at the rear of the fire truck 10. The largeconcentration of interface modules 20 and 30 at the front of the firetruck 10 is caused by the large number of switches (including those withintegral LED feedback output devices) located in a cab of the fire truck10, as well as the large number of other output devices (gauges,lighting) which tend to be located in the cab or otherwise near thefront of the fire truck 10. The interface module 34 that is located inthe middle of the truck is used in connection with I/O devices 40 and 50that are located at the fire truck pump panel (i.e., the operator panelthat has I/O devices for operator control of the fire truck's pumpsystem). The interface module 35 that is located at the rear of the firetruck 10 is used in connection with lighting and other equipment at therear of the fire truck 10.

The advantage of distributing the interface modules 20 and 30 in thismanner can be more fully appreciated with reference to FIG. 2, whichshows the interconnection of the interface modules 20 and 30. As shownin FIG. 2, the interface modules 20 and 30 receive power from a powersource 100 by way of a power transmission link 103. The powertransmission link 103 may comprise for example a single power line thatis routed throughout the fire truck 10 to each of the interface modules20 and 30. The interface modules then distribute the power to the outputdevices 50, which are more specifically designated with the referencenumbers 51 a, 52 a, 53 a, 54 a-c, 55 a-c, 56 a-b, 57 a-c and 58 a-d inFIG. 2.

It is therefore seen from FIGS. 1 and 2 that the relative distributionof the interface modules 20 and 30 throughout the fire truck 10 incombination with the arrangement of the power transmission link 103allows the amount of wiring on the fire truck 10 to be dramaticallyreduced. The power source 100 delivers power to the interface modules 20and 30, which act among other things as power distribution centers, andnot directly to the output devices 50. Because the interface modules 20and 30 are located so closely to the I/O devices 40 and 50, most of theI/O devices can be connected to the interface modules 20 and 30 usingonly a few feet of wire or less. This eliminates the need for a wireharness that extends the length of the fire truck (about forty feet) toestablish connections for each I/O devices 40 and 50 individually.

Continuing to refer to FIG. 2, the switch interface modules 20 and theinterconnection of the interface modules 20 with various I/O deviceswill now be described in greater detail. The interface modules 20 aremicroprocessor-based, as previously noted, and include a microprocessorthat executes a program to enable communication over the communicationnetwork 60, as detailed below.

The same or a different microprocessor of the interface modules 20 mayalso be used to process input signals received from the input devices40. In particular, the interface modules 20 preferably perform debouncefiltering of the switch inputs, so as to require that the position ofthe switch become mechanically stable before a switch transition isreported to the central control unit 14. For example, a delay of fiftymilliseconds may be required before a switch transition is reported.Performing this filtering at the interface modules 20 reduces the amountof processing that is required by the central control unit 14 tointerpret switch inputs, and also reduces the amount of communicationthat is required over the communication network 60 because each switchtransition need not be reported.

Physically, the interface modules 20 may be placed near the headliner ofa cab 17 of the fire truck 10. Traditionally, it is common practice tolocate panels of switches along the headliner of the cab for easy accessby an operator of the fire truck. Additionally, as detailed below, inthe preferred embodiment, the interface modules 20 are connected toswitches that have integrally fabricated LEDs for indicating the stateof the output device controlled by the switch to provide maximumoperator feedback. These LEDs are output devices which are connected tothe interface modules 20. Therefore, by locating the interface modulesnear the headliner of the cab, the amount of wiring required to connectthe interface modules 20 not only to the switches and but also to theLED indicators is reduced.

In the preferred embodiment, the interface modules 20 have between tenand twenty-five each of inputs and outputs and, more preferably, havesixteen digital (on/off switch) inputs and sixteen LED outputs. Most ofthese inputs and outputs are utilized in connection with switches havingintegrally fabricated LEDs. However, it should be noted that there neednot be a one-to-one correspondence between the switches and the LEDs,and that the inputs and the outputs of the interface modules 20 need notbe in matched pairs. For example, some inputs may be digital sensors(without a corresponding output device) and some of the outputs may beordinary digital indicators (without a corresponding input device).Additionally, the LED indicators associated with the switch inputs forthe interface module 21 could just as easily be driven by the interfacemodule 23 as by the interface module 21, although this arrangement isnot preferred. Of course, it is not necessary that all of the inputs andoutputs on a given interface module 20 be utilized and, in fact, it islikely that some will remain unutilized.

One way of establishing a dedicated link between the I/O devices 40 and50 and the interface modules 20 is through the use of a simple hardwiredlink. Considering for example an input device which is a switch, oneterminal of the switch may be connected (e.g., by way of a harnessconnector) to an input terminal of the interface module 20 and the otherterminal of the switch may be tied high (bus voltage) or low (ground).Likewise, for an output device which is an LED, one terminal of the LEDmay be connected to an output terminal of the interface module 20 andthe other terminal of the LED may again be tied high or low. Otherdedicated links, such as RF links, could also be used.

To provide maximum operator feedback, the LEDs that are located with theswitches have three states, namely, off, on, and blinking. The off stateindicates that the switch is off and therefore that the devicecontrolled by the switch is off. Conversely, the on state indicates thatthe switch is on and that the device controlled by the switch is on. Theblinking state indicates that the control system 12 recognizes that aswitch is on, but that the device which the switch controls isnevertheless off for some other reason (e.g., due to the failure of aninterlock condition, or due to the operation of the load manager or loadsequencer). Notably, the blinking LED feedback is made possible by thefact that the LEDs are controlled by the control unit 14 and notdirectly by the switches themselves, since the switches themselves donot necessarily know the output state of the devices they control.

A specific example will now be given of a preferred interconnection ofthe interface modules 21, 22, and 23 with a plurality of I/O devices 40and 50. Many or all of the I/O devices 40 and 50 could be the same asthose that have previously been used on fire trucks. Additionally, itshould be noted that the example given below is just one example, andthat a virtually unlimited number of configurations are possible. Thisis especially true since fire trucks tend to be sold one or two at atime and therefore each fire truck that is sold tends to be unique atleast in some respects.

In FIG. 2, the interface module 21 receives inputs from switches 41 athat control the emergency lighting system of the fire truck. Aspreviously noted, the emergency lighting system includes the flashingemergency lights (usually red and white) that are commonly associatedwith fire trucks and that are used to alert other motorists to thepresence of the fire truck on the roadway or at the scene of a fire. Oneof the switches 41 a may be an emergency master on/off (E-master) switchused to initiate load sequencing, as described in greater detail below.The interface module 21 may also be connected, for example, to switches41 b that control the emergency siren and horn. The interface module 21is also connected to LEDs 51 a that are integrally located in theswitches 41 a and 41 b and that provide operator feedback regarding thepositions of the switches 41 a and 41 b, as previously described.

The interface module 22 receives inputs from switches 42 a that controllighting around the perimeter of the fire truck 10, switches 42 b thatcontrol scene lighting, and switches 42 c that control lighting whichaids the operators in viewing gauges and other settings at the pumppanel. The interface module 22 is also connected to LEDs 52 a that areintegrally located in the switches 42 a, 42 b and 42 c and that provideoperator feedback regarding the positions of the switches 42 a, 42 b and42 c.

The interface module 23 receives inputs from switches 43 a that controlheating and air conditioning, and switches 43 b that controlsmiscellaneous other electrical devices. The interface module 23 isconnected to LED indicators, some of which may be integrally locatedwith the switches 43 a and 43 b and others of which may simply be an LEDindicator that is mounted on the dashboard or elsewhere in the cab ofthe fire truck 10.

Continuing to refer to FIG. 2, the vehicle interface modules 30 and theinterconnection of the interface modules 20 with various I/O deviceswill now be described in greater detail. As previously mentioned, theinterface modules 30 are distinguishable from the interface modules 20mainly in that the interface modules 30 are capable of handling bothanalog and digital inputs and outputs, and in that they are capable ofproviding more output power to drive output devices such asdigitally-driven gauges, solenoids, and so on. The interface modules 30preferably have between fifteen and twenty-five each inputs and outputsand, more preferably, have twenty inputs (including six digital inputs,two frequency counter inputs, and six analog inputs) and twenty outputs(including six outputs that are configurable as analog outputs).

Like the interface modules 20, the interface modules 30 aremicroprocessor-based and include a microprocessor that executes aprogram to enable communication over the communication network 60. Thesame or a different microprocessor of the interface modules 30 may alsobe used to process input signals received from the input devices 40 andto process output signals transmitted to the output devices 50.

For the interface modules 30, this processing includes not only debouncefiltering, in the case of switch inputs, but also a variety of othertypes of processing. For example, for analog inputs, this processingincludes any processing that is required to interpret the inputs fromanalog-to-digital (A/D) converters, including converting units. Forfrequency inputs, this processing includes any processing that isrequired to interpret inputs from frequency-to-digital converters,including converting units. This processing also includes other simplefiltering operations. For example, in connection with one analog input,this processing may include notifying the central control unit 14 of thestatus of an input device only every second or so. In connection withanother analog input, this processing may include advising the centralcontrol unit 14 only when the status of the input device changes by apredetermined amount. For analog output devices, this processingincludes any processing that is required to interpret the outputs fordigital-to-analog (D/A) converters, including converting units. Fordigital output devices that blink or flash, this processing includesimplementing the blinking or flashing (i.e., turning the output deviceon and off at a predetermined frequency) based on an instruction fromthe central control unit 14 that the output device should blink orflash. In general, the processing by the interface modules 30 reducesthe amount of information which must be communicated over thecommunication link, and also reduces the amount of time that the centralcontrol unit 14 must spend processing minor changes in analog inputstatus.

Preferably, the configuration information required to implement the I/Oprocessing that has just been described is downloaded from the centralcontrol unit 14 to each interface module 30 (and each interface module20) at power-up. Additionally, the harness connector that connects toeach of the interface modules 20 and 30 are preferably electronicallykeyed, such that being connected to a particular harness connectorprovides the interface modules 20 and 30 with a unique identificationcode (for example, by tying various connector pins high and low toimplement a binary code). The advantage of this approach is that theinterface modules 20 and 30 become interchangeable devices that arecustomized only at power-up. As a result, if one of the interfacemodules 30 malfunctions, for example, a new interface module 30 can beplugged into the control system 12, customized automatically at power-up(without user involvement), and the control system 12 then becomes fullyoperational. This enhances the maintainability of the control system 12.

A specific example will now be given of a preferred interconnection ofthe interface modules 31, 32, and 33 with a plurality of I/O devices 40and 50. This example continues the example that was started inconnection with the interface modules 21, 22, and 23. Again, it shouldbe noted that the configuration described herein is just one example.

The interface modules 31, 32, 33, 34 and 35 all receive inputs fromadditional switches and sensors 44 a, 45 a, 46 a, 47 a and 48 a. Theswitches may be additional switches that are located in the cab of thefire truck or elsewhere throughout the vehicle, depending on thelocation of the interface module. The sensors may be selected ones of avariety of sensors that are located throughout the fire truck. Thesensors may be used to sense the mechanical status of devices on thefire truck, for example, whether particular devices are engaged ordisengaged, whether particular devices are deployed, whether particulardoors on the fire truck are open or closed, and so on. The sensors mayalso be used to sense fluid levels such as fuel level, transmissionfluid level, coolant level, foam pressure, oil level, and so on.

In addition to the switches and sensors 44 a, the interface module 31 isalso connected to a portion 54 a of the emergency lighting system. Theemergency lighting system includes emergency lights (usually red andwhite) at the front, side and rear of the fire truck 10. The emergencylights may, for example, be in accordance with the guidelines providedby the National Fire Protection Association. Because the interfacemodule 31 is located at the front of the fire truck, the interfacemodule 31 is connected to the red and white emergency lights at thefront of the fire truck.

The interface module 31 is also connected to gauges and indicators 54 bwhich are located on the dashboard of the fire truck 10. The gauges mayindicate fluid levels such as fuel level, transmission fluid level,coolant level, foam pressure, oil level and so on. The indicators mayinclude, for example, indicators that are used to display danger,warning and caution messages, warning lights, and indicators thatindicate the status of various mechanical and electrical systems on thefire truck. The interface module 31 may also be connected, for example,to an emergency sound system including an emergency siren and emergencyair horns 54 c, which are used in combination with the emergency lights54 a.

In addition to the switches and sensors 45 a, the interface module 32 isalso connected to perimeter lighting 55 a, scene lighting 55 b andutility lighting 55 c. The perimeter lighting 55 a illuminates theperimeter of the fire truck 10. The scene lighting 55 b includes brightflood lights and/or spot lights to illuminate the work area at a fire.The utility lighting 55 c includes lighting used to light operatorpanels, compartments and so on of the fire truck 10.

In addition to the switches and sensors 46 a, the interface module 33 isalso connected to PTO sensors 46 b. The PTO sensors 46 b monitor thestatus of a power take-off mechanism 97 (see FIG. 1), which divertsmechanical power from the engine/transmission from the wheels to othermechanical subsystems, such as the pump system, an aerial system and soon. The interface module 33 is also connected to a portion 56 a of theFMVSS (Federal Motor Vehicle Safety Standard) lighting. The FMVSSlighting system includes the usual types of lighting systems that arecommonly found on most types of vehicles, for example, head lights, taillights, brake lights, directional lights (including left and rightdirectionals), hazard lights, and so on. The interface module 33 is alsoconnected to the heating and air conditioning 56 b.

In addition to the switches and sensors 47 a, the interface module 34,which is disposed near the pump panel, is connected to pump panelswitches and sensors 47 a, pump panel gauges and indicators 57 a, pumppanel lighting 57 b, and perimeter lighting 57 c. The pump system may bemanually controlled or may be automatically controlled through the useof electronically controlled valves. In either case, the various fluidpressures are measured by sensors and displayed on the gauges andindicators 57 a.

Finally, in addition to the switches and sensors 48 a, the interfacemodule 35 is also connected to emergency lighting 58 a, scene lighting58 b, FMVSS lighting 58 c, and the utility lighting 58 d. These lightingsystems have been described above.

The interface modules 20 and the interface modules 30 are connected tothe central control unit 14 by the communication network 60. Thecommunication network may be implemented using a network protocol, forexample, which is in compliance with the Society of Automotive Engineers(SAE) J1708/1587 and/or J1939 standards. The particular network protocolthat is utilized is not critical, although all of the devices on thenetwork should be able to communicate effectively and reliably.

The transmission medium may be implemented using copper or fiber opticcable. Fiber optic cable is particularly advantageous in connection withfire trucks because fiber optic cable is substantially immune toelectromagnetic interference, for example, from communication antennaeon mobile news vehicles, which are common at the scenes of fires.Additionally, fiber optic cable is advantageous because it reduces RFemissions and the possibility of short circuits as compared tocopper-based networks. Finally, fiber optic cable is advantageousbecause it reduces the possibility of electrocution as compared tocopper in the event that the cable accidentally comes into contact withpower lines at the scene of a fire.

Also connected to the communication network 60 are a plurality ofdisplays 81 and 82. The displays 81 and 82 permit any of the datacollected by the central control unit 14 to be displayed to thefirefighters in real time. In practice, the data displayed by thedisplays 81 and 82 may be displayed in the form of text messages and maybe organized into screens of data (given that there is too much data todisplay at one time) and the displays 81 and 82 may include membranepushbuttons that allow the firefighters to scroll through, page through,or otherwise view the screens of data that are available. Additionally,although the displays 81 and 82 are both capable of displaying any ofthe information collected by the central control unit 14, in practice,the displays 81 and 82 are likely to be used only to display selectedcategories of information. For example, assuming the display 81 islocated in the cab and the display 82 is located at the pump panel, thedisplay 81 is likely to be used to display information that pertains todevices which are controlled from within the cab, whereas the display 82is likely to be used to display information pertaining to the operationof the pump panel. Advantageously, the displays 81 and 82 givefirefighters instant access to fire truck information at a singlelocation, which facilitates both normal operations of the fire truck aswell as troubleshooting if problems arise.

Also shown in FIG. 2 is a personal computer 85 which is connected to thecontrol unit 14 by way of a communication link 86, which may be a modemlink, an RS-232 link, an Internet link, and so on. The personal computer85 allows diagnostic software to be utilized for remote or localtroubleshooting of the control system 12, for example, through directexamination of inputs, direct control of outputs, and viewing andcontrolling internal states, including interlock states. Because all I/Ostatus information is stored in the central control unit 14, thisinformation can be easily accessed and manipulated by the personalcomputer 85. If a problem is encountered, the personal computer can beused to determine whether the central control unit 14 considers all ofthe interface modules 20 and 30 to be “on-line” and, if not, theoperator can check for bad connections and so on. If a particular outputdevice is not working properly, the personal computer 85 can be used totrace the I/O status information from the switch or other input devicethrough to the malfunctioning output device. For example, the personalcomputer 85 can be used to determine whether the switch state is beingread properly, whether all interlock conditions are met, and so on.

The personal computer 85 also allows new firmware to be downloaded tothe control unit 14 remotely (e.g., from a different city or state orother remote location by way of the Internet or a telephone link) by wayof the communication link 86. The firmware can be firmware for thecontrol unit 14, or it can be firmware for the interface modules 20 and30 that is downloaded to the control unit 14 and then transmitted to theinterface modules 20 and 30 by way of the communication network 60.

Finally, referring back to FIG. 1, several additional systems are shownwhich will now be briefly described before proceeding to a discussion ofthe operation of the control system 12. In particular, FIG. 1 shows anengine system including an engine 92 and an engine control system 91, atransmission system including a transmission 93 and a transmissioncontrol system 94, and an anti-lock brake system including an anti-lockbrake control system 95 and anti-lock brakes 96. The transmission 93 ismechanically coupled to the engine 92, and is itself furthermechanically coupled to a PTO system 97. The PTO system 97 allowsmechanical power from the engine to be diverted to water pumps, aerialdrive mechanisms, stabilizer drive mechanisms, and so on. Incombination, the engine system, the transmission system and the PTOsystem form the power train of the fire truck 10.

The control systems 92, 94 and 95 may be connected to the centralcontrol unit 14 using the same or a different communication network thanis used by the interface modules 30 and 40. In practice, the controlsystems 92, 94 and 95 are likely to be purchased as off-the-shelfsystems, since most fire truck manufacturers purchase rather thanmanufacture engine systems, transmission systems and anti-lock brakesystems. As a result, it is likely that the control systems 92, 94 and95 will use a variety of different communication protocols and thereforethat at least one additional communication network will be required.

By connecting the systems 92, 94 and 95 to the central control unit 14,an array of additional input status information becomes available to thecontrol system 12. For example, for the engine, this allows the centralcontrol unit 14 to obtain I/O status information pertaining to enginespeed, engine hours, oil temperature, oil pressure, oil level, coolantlevel, fuel level, and so on. For the transmission, this allows thecentral control unit 14 to obtain, for example, information pertainingtransmission temperature, transmission fluid level and/or transmissionstate (1st gear, 2nd gear, and so on). Assuming that an off-the-shelfengine or transmission system is used, the information that is availabledepends on the manufacturer of the system and the information that theyhave chosen to make available.

Connecting the systems 92, 94 and 95 to the central control unit 14 isadvantageous because it allows information from these subsystems to bedisplayed to firefighters using the displays 81 and 82. This also allowsthe central control unit 14 to implement various interlock conditions asa function of the state of the transmission, engine or brake systems.For example, in order to turn on the pump system (which is mechanicallydriven by the engine and the transmission), an interlock condition maybe implemented that requires that the transmission be in neutral or 4thlockup (i.e., fourth gear with the torque converter locked up), so thatthe pump can only be engaged when the wheels are disengaged from thepower train. The status information from these systems can therefore betreated in the same manner as I/O status information from any otherdiscrete I/O device on the fire truck 10. It may also be desirable toprovide the central control unit 14 with a limited degree of controlover the engine and transmission systems, for example, enabling thecentral control unit 14 to issue throttle command requests to the enginecontrol system 91. This allows the central control unit to control thespeed of the engine and therefore the voltage developed across thealternator that forms part of the power source 100.

2. Manner of Operation of Preferred Fire Truck Control System

The operation of the control system 12 will now be described in greaterdetail, including the manner in which interlock control, loadmanagement, and load sequencing are implemented by the control system12.

a. Operation Overview and Interlock Control

Referring now to FIGS. 3-5, a first example of the operation of thecontrol system 12 is given. FIG. 3 is a block diagram of the controlsystem 12, which has been simplified to the extent that some of thestructure shown in FIGS. 1-2 is not shown in FIG. 3. Additionally, FIG.3 shows in greater detail a switch 341 (which is one of the switches 41a in FIG. 2), rear scene lights 351 (which are part of the rear scenelighting 58 b in FIG. 2), and an LED indicator 352 (which is one of theswitch LED feedback indicators 51 a in FIG. 2). The rear scene lights351 are considered a single output device since they are both connectedto one output of the interface module 35, even though there are in facttwo lights. Finally, the central control unit 14 is also shown toinclude an interlock system 316, which is implemented in the controlprogram 16 executed by the microprocessor 15.

FIG. 4 is a flowchart showing the operation of the control system 12 toactivate the rear scene lights 351 in response to an input signalreceived from the switch 341. One of the advantages of the controlsystem 12 is that input signals from the input devices 40 are processedby the control unit 14 and do not directly control the output devices50. Switches represent user input commands but do not close theelectrical circuit between the power source 100 and the output devicecontrolled by the switch. As will be described below, this simplifiescontrol system wiring and makes possible more flexible control of outputdevices.

In order to highlight this aspect of the control system 12, it will beassumed that the switch 341 is a soft toggle switch. Thus, the switch341 is physically a momentary switch, i.e., a switch that closes whenpressed but, when pressure is removed, automatically returns to an openposition. The control system 12 makes the switch 341 emulate a latchedswitch, i.e., a switch that remains closed when pressed and returns toan open position only when pressed again.

First, in step 401, the switch 341 transmits an input signal to theinterface module 21. The input signal is transmitted to the interfacemodule 21 as a result of a change in the status of the switch, forexample, when an operator presses the switch. The input signal from theswitch 341 is transmitted to the interface module 21 by way of ahardwired communication link 101 which may, for example, comprise a wirethat connects a terminal of the switch 341 to an input terminal of theinterface module 21 (with the other terminal of the switch 341 beingtied high or low). Other types of dedicated links may also be used.

At step 402, the interface module 21 processes the input signal. For theswitch 341, the interface module performs debounce filtering, forexample, by waiting until the mechanical position of the switchstabilizes (e.g., fifty milliseconds) before the transmitting the inputsignal to the control unit 14.

At step 403, the interface module 21 transmits the input signal in theform of a network message to the control unit 14 (“ECU” in FIG. 4). Thenetwork message is sent by way of the communication network 60 and, inparticular, by way of a network communication link 61 that links theinterface module 21 to the control unit 14.

At step 404, the control unit 14 processes the input signal. Aspreviously noted, the switch 341 is physically a momentary switch (i.e.,a switch that closes when pressed but, when pressure is removed,automatically returns to an open position) but is made to emulate alatched switch (i.e., a switch that remains closed when pressed andreturns to an open position only when pressed again). Accordingly, toprocess the input signal, the control unit 14 first determines that theswitch 341 has experienced an off→on transition (i.e., because theswitch 341 was previously off but is now on), and then determines thatthe present state of the rear scene lights 351 are off. Accordingly, atstep 405, the control unit 14 generates a first control signal to turnon the rear scene lights 351, as well as a second control signal to turnon LED indicator 352.

At step 406, the control unit 14 transmits the first control signal inthe form of a second network message to the interface module 35. Thenetwork message is sent by way of the communication network 60 and, inparticular, by way of a network communication link 65 that links thecentral control unit 14 to the interface module 35. In practice, thenetwork communication link 65 may utilize some or all of the samephysical media utilized by the network communication link 61, dependingon the network architecture that is utilized. In the illustratedembodiment a bus architecture is utilized, but it should be understoodof course that other types of network architectures (such as ring orstar architectures) may also be utilized.

At step 407, the interface module 35 transmits the first control signalto the rear scene lights 351. The control signal is transmitted in theform of a power control signal on a hardwired communication link 105.The hardwired communication link 105 may, for example, comprise a wirethat connects a terminal of the switch 341 to an input terminal of theinterface module 21. The power control signal from the interface module35 has two states, namely, an “on” state in which power is provided tothe lighting system 351 and an “off” in which power is not provided tothe lighting system 351.

At step 408, the control unit 14 transmits the second control signal tothe interface module 21 by way of the network communication link 61 inthe form of a third network message. At step 409, the interface module21 transmits the second control signal to the LED indicator 352 in theform of a power control signal on a hardwired communication link 102. Aspreviously noted, the LED indicator 352 is located integrally with theswitch 341 (e.g., at the tip of the lever of the switch 341, in a mannersuch that the LED is clearly associated with the switch 341). Therefore,when the second control signal is transmitted to the LED indicator 352,thereby turning on the LED indicator 352, the LED indicator providesfeedback to the operator regarding the status of the rear scene lights351. In the present situation, the on state of the LED indicator 352indicates that the rear scene lights 351 are on.

When the switch 341 is released, another input signal (not shown) issent to the interface module 21 which indicates that the input state ofthe switch has changed from on to off. The control unit 14 recognizesthe on→off transition, but ignores the transition pursuant to making theswitch 341 emulate a latched switch.

It may be noted therefore that the switch 341 does not complete theelectrical power circuit for the rear scene lights 351. When the switch341 is released, the switch 341 opens but this change does not cause anychange in the output status of the scene lights 351. The opportunity forthe central control unit 14 to process the input signal from the switch341 (as well as other input devices) makes the control system 12 moreflexible and robust while at the same time reducing wiring and thereforereducing the number of failure points.

For example, a feature that is easily implemented in the control system12 is two-way or, more generally, N-way switching. To implement N-wayswitching, it is only necessary to define N switches as inputs thatcontrol a given lighting system, and to program the control unit 14 totoggle the state of the lighting system every time the latched state ofone of the N switches changes. A complicated and wiring-intensive N-wayswitching circuit is not required because the control logic required toimplement N-way switching is not hardwired but rather is programmed intothe control unit 14. Another feature that is easily implemented isprogressive switching, in which the control unit 14 responds differentlyeach time a given switch is pressed.

In addition to the advantages that are achieved due to the processing ofthe inputs, additional advantages are achieved in connection withprocessing the outputs. Thus, another advantage of the control system 12is that the outputs are capable of multiple modes of operation, withoutany additional hardware, depending on the mode of operation of thevehicle. Thus, the same output device can have a digital mode ofoperation, an analog mode of operation, and a flashing mode ofoperation. For example, the same set of lights can be made to operate ashigh beam headlights at night (digital), as day-time running lightsduring the day (analog), and as flashing white lights in an emergencysituation. (This is especially true if analog outputs are implementedusing pulse width modulation to emulate a true analog-type output.)Because specialized hardware for each mode of operation is not required,it is much easier to provide any given output device with the ability tooperate in different modes.

Another advantage with respect to the processing of outputs is that thecentral control unit 14 has the ability to synchronize or desynchronizedifferent output devices. For example, in connection with the flashingemergency lights, it is possible to more precisely control the emergencylights and to have different lights flashing with exactly the samefrequency but at a different phase. This prevents multiple sets oflights from undesirably turning on at the same time. For fire truckswith circuit breakers, this situation is undesirable because it cancause the current draw of the multiple sets of lights to trip a circuitbreaker, thereby rendering the flashing emergency lights inoperativealtogether.

Referring now to FIG. 5, the operation of the control system 12 todisengage the rear scene lights 351 in response to a changed interlockcondition is illustrated. Federal Motor Vehicle Safety Standard (FMVSS)regulations prohibit the use of white lights on the back of a vehiclewhen the vehicle is moving forward. This regulation prevents otherdrivers from confusing the vehicle with oncoming traffic. Therefore, ifa fire truck at the scene of a fire has white rear scene lights turnedon and a firefighter decides to move the fire truck, the firefightermust first remember to turn off the white rear scene lights. FIG. 5illustrates the operation of the control system to implement aninterlock system 316 that eliminates the need for the firefighter tohave to remember to turn off the rear scene lights in this situation.

To implement this type of control, a sensor 342 that monitors the statusof the parking brake is utilized. The control rules governing theinterlock condition for this example are then as follows. The rear scenelights 351 should disengage when the parking brake is disengaged.However, the rear scene lights are allowed to be on when the parkingbrake is off. Therefore, the rear scene lights are turned off only whenthere is an on→off transition of the parking brake and, otherwise, therear scene lights are allowed to be on.

Accordingly, by way of example, the parking brake is turned off at step501. At step 502, the parking brake sensor 342 transmits an input signalto the interface module 31. At step 503, the interface module 31processes the input signal. For example, the interface module 31performs debounce filtering to require stabilization of the mechanicalstate of the sensor before a state change is recognized.

At step 504, the interface module 31 transmits the input signal in theform of a network to the control unit 14 by way of a networkcommunication link 67. At step 505, the control unit 14 processes theinput signal. For example, the control unit 14 determines that the rearscene lights 351 are on, and that there has been an on→off transition inthe state of the parking brake sensor 342. Accordingly, at step 506, thecontrol unit 14 generates a first control signal to turn off the rearscene lights 351 and a second control signal to cause the LED indicator352 to blink.

At step 507, the control unit 14 transmits the first control signal inthe form of a network message to the interface module 35. In turn, atstep 508, the interface module 35 transmits the control signal to therear scene light lights 351, thereby causing the rear scene lights toturn off.

At step 509, the control unit 14 transmits the second control signal inthe form of a network message to the interface module 21. In turn, atstep 510, the interface module 35 transmits the control signal to theLED indicator 352, thereby causing the LED indicator 352 to blink. Theblinking state of the LED indicator 352 indicates to the operator thatthe control unit 14 considers the switch 341 to be on, but that the rearscene lights 351 are nevertheless off because some other condition onthe fire truck is not met. In this case, the rear scene lights 351 areoff due to the on→off transition in the state of the parking brake. Inthis way, operator feedback is maximized.

The flowchart of FIG. 4, at step 510, shows the use of a single controlsignal to cause the LED indicator 352 to blink. In practice, theblinking of the LED indicator 352 may be achieved in a variety of ways.For example, if a simple hardwired connection between the interfacemodule 21 and the LED indicator 352 is utilized, the interface module 21may periodically provide periodic on and off control signals to the LEDindicator 352 by periodically applying power to the output terminal thatis connected to the LED indicator 352. Alternatively, if a blinkermodule is utilized, the interface module may provide a single controlsignal to the blinker module, which then controls blinking of the LEDindicator 352.

If the operator then pushes and releases the switch 341 a second timewhile the parking brake is off, the process in FIG. 4 is repeated andthe rear scene lights 351 turn on. In this case, the rear scene lights351 turn on even though the parking brake is off, because the controlsystem 12 only prevents the rear scene lights from being on when theparking brake is first released. If the operator pushes and releases theswitch 341 a third time, the control system 12 turns off the rear scenelights 351.

b. Load Management

Referring now to FIGS. 6-8, a second example of the operation of thecontrol system 12 is given. FIG. 6 is another block diagram of thecontrol system 12, which has been simplified to the extent that some ofthe structure shown in FIGS. 1-2 is not shown in FIG. 6. Additionally,FIG. 6 shows a plurality of output devices 651, 652, 653 and 654 thathave load management priority levels equal to one, two, three and four,respectively. The output devices 651, 652, 653 and 654 are exemplaryones of the output devices 50 of FIGS. 1-2. Finally, the central controlunit 14 is shown to include a load manager 616, which is implemented inthe control program 16 executed by the microprocessor 15.

Because the output devices 651, 652, 653 and 654 are assigned fourdifferent load management priority levels, the load manager 616 isreferred to as a four level load manager. As will become apparent,implementing a load manager with additional priority levels can beachieved simply by defining additional priority levels. Indeed, it iseven possible for the load manager 616 to have the same number of levelsas there are output devices, by assigning every output device adifferent priority level and by shedding the output devices one by oneas the battery voltage drops.

FIG. 7 is a flowchart showing the operation of the load manager 616. Inparticular, the flowchart of FIG. 7 describes the operation of the loadmanager 616 to turn off output devices in layers when the system voltagedecreases. It may be noted that a similar approach may be used when thesystem voltage increases, in which case devices that are sensitive toover voltage conditions may be turned off in layers as the systemvoltage increases.

At step 701, the load manager initializes tracking variables and setsthe active priority equal to zero. The active priority is the prioritylevel that is currently shed. (In the described embodiment, theparameter N is typically equal to the active priority minus one.However, the parameter N could also simply be equal to the activepriority.) Therefore, assuming that none of the output devices 651, 652,653, 654 are shed, then the active priority level is equal to zero. Theactive priority increases as shedding occurs.

At step 702, the control unit 14 determines whether the battery voltagehas decreased to the priority N load shed voltage. Initially, thetracking variable N is equal to one and so, initially, the control unit14 is determining in step 702 whether the battery voltage has decreasedenough for the first layer of shedding to occur. If the battery voltagehas not decreased, then the control unit 14 continues to monitor thebattery voltage until the priority 1 load shed voltage is reached.

At step 703, when the battery voltage has decreased to the priority 1load shed voltage, then the control unit 14 starts a load shed timer.The purpose of the load shed timer is to ensure that a temporaryreduction in the battery voltage (for example, caused by engagement ofan output device that draws a significant amount of current) is notmisinterpreted as the battery running out of power, so that the controlunit 14 does not unnecessarily start shedding output devices.

The control unit 14 continues to monitor the battery voltage at step 704until the load shed timer elapses at step 705. During this time, thecontrol unit 14 continues to monitor whether the battery voltage isequal to or less than the priority 1 load shed voltage. If the batteryreturns above the load shed voltage, then that indicates only atemporary voltage reduction has occurred and therefore the processreturns to step 702 after the active priority is set equal to N−1 atstep 706. In this case, since N is equal to one, the active priorityremains equal to zero, in other words, no output devices are shed.

If the battery voltage is still equal to or less than the priority 1load shed voltage when the load shed timer elapses at step 705, then theprocess proceeds to step 707. At step 707, the control unit 14determines whether any of the priority 1 output devices are active. Ifnone of the priority 1 output devices 651 are active, then N isincremented by one, and the process proceeds to step 702. At step 702,the control unit 14 determines whether the battery voltage has decreasedto the priority 2 load shed voltage. Thus, because the battery voltageis low, but there were no priority 1 output devices 651 to shed at step707, the control unit determines whether it is appropriate to startshedding priority 2 output devices 652. The control unit 14 repeats theprocess and continues to search for a level of devices to shed untileither the battery voltage is not low enough to justify shedding thenext layer of devices (in which case the process proceeds to step 706,where the active priority is set equal to the highest level at which thebattery voltage is low enough to cause shedding, if there were outputdevices to shed, and then the process returns to step 702) or until step707 is answered affirmatively (in which case the process proceeds tostep 709, where the active priority is set equal to the priority levelat which output devices are available for shedding, and then the processproceeds to step 710).

At step 710, these output devices are shed, the variable N isincremented, and the process proceeds to step 702 where the control unit14 determines whether the battery voltage is less than the load shedvoltage of the next priority level. The process then repeats until thebattery voltage is greater than the load shed voltage of the nextpriority level.

When the active priority level becomes non-zero, the control unit 14denies all requests for engagement of devices that have a priority levelwhich is equal to or less than the active priority level. Thus, alldevices that have a priority level which is equal to or less than theactive priority level remain off, at least until the battery voltageincreases and it becomes appropriate to restore some output devices, asdescribed below in connection with FIG. 8.

As previously described, some output devices are controlled by switchesthat are integrally fabricated with an LED indicator. For such outputdevices, the control unit 14 causes the appropriate LED indicator tostart blinking, thereby advising the operator that the switch isrecognized by the control unit 14 as being turned on, but that theassociated output device is nevertheless disengaged because it is beingload managed. The process of making indicator LEDs blink was describedpreviously in connection with FIG. 4.

Referring now to FIG. 8, a process for restoring power to output devicesis illustrated. The battery is connected to the alternator and, ifloading is reduced enough, the battery will begin to regain voltage.Therefore, it may become appropriate to restore power to at least someoutput devices. The process shown in FIG. 8 for restoring power isessentially the opposite of the process shown in FIG. 7. The process ofFIG. 8 may be performed in time alternating fashion with respect to theprocess of FIG. 7.

In particular, at step 801, it is determined whether the battery voltagehas increased to the priority N load restore voltage. For example, ifthe active priority is currently set equal to three, then step 801determines whether the battery voltage is greater than or equal to thepriority 3 load restore voltage. The priority 3 load restore voltage ispreferably larger than the priority 3 load shed voltage in order toimplement a hysteresis effect that avoids output devices from flickeringon and off.

At step 802, when the battery voltage has increased to the priority 3load restore voltage, then the control unit 14 starts a load restoretimer. The purpose of the load restore timer is to ensure that atemporary voltage surge is not misinterpreted as the battery regainingpower, so that the control unit 14 does not inappropriately startrestoring output devices.

The control unit continues to monitor the battery voltage at step 803until the load restore timer elapses at step 804. During this time, thecontrol unit 14 continues to monitor whether the battery voltage isstill equal to or greater than the priority 3 load shed voltage. If thebattery returns below the load restore voltage, then that indicates onlya temporary voltage surge and therefore the process returns to step 801after the active priority is set equal to N−1 at step 805. In this case,since N is equal to four (N is always one greater than the activepriority in the described embodiment), the active priority remains equalto three, in other words, no output devices are restored.

If the battery voltage is still equal to or greater than the priority 3load restore voltage at step 804, then the process proceeds to step 806.At step 806, the control unit 14 determines whether any of the priority3 output devices 653 are inactive. If none of the priority 3 outputdevices are inactive, then N is decremented by one, and the processproceeds to step 801. At step 801, the control unit 14 determineswhether the battery voltage has increased to the priority 2 load restorevoltage. Thus, because the battery voltage has increased, but there wereno priority 3 output devices 653 to restore at step 806, the controlunit determines whether it is appropriate to start restoring priority 2output devices 652. The control unit 14 continues to search for a levelof devices to restore until either the battery voltage is not highenough to justify restoring the next layer of devices (in which case theprocess proceeds to step 805, where the active priority is set equal tothe highest level at which the battery voltage is high enough to permitrestoring, if there were output devices to restore, and then the processreturns to step 801) or until step 806 is answered affirmatively (inwhich case process proceeds to step 808, where the active priority isset equal to the priority level at which output devices are availablefor restoring, and then the process proceeds to step 809).

At step 809, these output devices are restored, the variable N isdecremented, and the process proceeds to step 702 where the control unit14 determines whether the battery voltage is greater than the loadrestore voltage of the next priority level. The process then continuesuntil the battery voltage is less than the load restore voltage of thenext priority level, or until all devices have been restored. Once alevel of output devices has been restored, the control unit 14 startsaccepting requests to turn on output devices having the restoredpriority level.

The implementation of the load manager 616 in the control unit 14permits a high degree of flexibility to be obtained. For example, thepriority level of output devices can be changed without requiring anyhardware changes. For example, air conditioning might be given a higherpriority in summer, when air conditioning is more critical for coolingoff firefighters that have been inside a burning building, and less of apriority in winter when the outside temperature may be below freezing.

Further, the priority of the output devices can change dynamically as afunction of the operating mode of the fire truck. Thus, in FIG. 6, theoutput device 658 is illustrated as having a priority X. The variable Xmay be set equal to one value for most operating conditions. However,upon receiving a request for the output device 658, the central controlunit can review the I/O state of the fire truck and, if predeterminedI/O conditions are met, give the output device 658 a higher loadmanagement priority level, thereby allowing the output device 658 toturn on. Because the load management priority level is asoftware-assigned value, and is not hardwired by relay logic, it ispossible to change the load management priority level of output devicesdynamically while the fire truck is operating at the scene of a fire.

An additional advantage of the control system 12 is that it is moreflexible and allows a higher level of load management granularity to beachieved. With the control system 12, it is possible to shed individualoutput devices instead of just groups of devices. For example, it ispossible to shed individual lights within a lighting system withoutturning off the whole lighting system.

Another advantage of the control system 12 is that it can be given theability to predict operational requirements of the fire truck, such thatpotential operational difficulties can be avoided. For example, with theload manager 616, the battery current draw may be monitored and very lowpriority loads may be preemptively shed in order to slow down or preventthe loss of battery power.

Another advantage of the control system 12 is that can be given theability to perform prognoses of various system conditions and use theinformation obtained to alleviate or prevent operational difficulties.For example, the load manager 616 can predict, based on a knowledge ofhow much battery current is being drawn, how long the battery will lastuntil it is necessary to start shedding output devices. Other examplesalso exist. For example, water flow from an on-board water supply can bemonitored and the amount of time remaining until water is depleted canbe displayed to an operator of the fire truck 10. This allowsfirefighters to know with greater accuracy how quickly they need to getthe fire truck connected to a fire hydrant before the water supply isdepleted. Similarly, for oxygen masks used in the basket of an aerial,oxygen flow can be monitored and the amount of time remaining untiloxygen is depleted can be displayed to an operator of the fire truck.Again, this allows firefighters to know with greater accuracy howquickly the oxygen supply should be replenished. Althoughconventionally, fire trucks have level indicators that indicate theamount of water or oxygen remaining, firefighters are generally moreconcerned about the amount of time remaining rather than the absolutequantity of water/oxygen remaining. This is especially true since thewater and oxygen flow rates can vary significantly during the operationof the fire truck.

C. Load Sequencing

Referring now to FIGS. 9, 10A, and 10B, a second example of theoperation of the control system 12 is given. FIG. 9 is another blockdiagram of the control system 12, which has been simplified to theextent that some of the structure shown in FIGS. 1-2 is not shown inFIG. 9. Additionally, FIG. 6 shows a plurality of switches 941-945, aplurality of emergency lighting subsystems 951-954, and a plurality ofLED indicators 955-959. The central control unit 14 includes a loadsequencer 916, which is implemented in the control program 16 executedby the microprocessor 15.

In FIGS. 9, 10A and 10B, the operation of the load sequencer isdescribed with respect to four emergency lighting subsystems 951-959. Itmay be noted that the load sequencer may be used in other situations tocontrol other output devices. For example, another load sequencer may beused when battery power is first applied, and another when the ignitionis first turned on.

The lighting subsystems 951-59 may each, for example, comprise oneemergency light or a set of emergency lights that are coupled to anoutput of one of the interface modules 30. Additionally, while only foursubsystems are shown, in practice the load sequencer may be used tocontrol additional emergency lighting subsystems.

The switches 941, 942, 943 and 944 respectively control the emergencylights 951, 952, 953 and 954. The remaining switch 945 is the E-masterswitch. For any given set of emergency lights, both the E-master switchand the respective switch 941-944 must be turned on. Initially, theprevious active on/off states of the switches 941-944, which have beenstored in non-volatile memory, are recalled. Then, when an emergencycall is received, an operator activates the E-master switch 945.

At step 1001, E-master switch 945 transmits an input signal to theinterface module 21. At step 1002, the interface module processes theinput signal. At step 1003, the interface module 21 transmits the inputsignal in the form of a network message to the central control unit 14.At step 1004, the central control unit processes input signal.

At step 1005, the control unit causes blinking of the LED indicators955-959 of the sequenced emergency lighting subsystems 951-954. Inparticular, the control unit transmits control signals (in the form ofnetwork messages) to the interface modules that are connected to the LEDindicators 955-959, which in turn transmit the control signals to theLED indicators 955-959 themselves, in the manner previously described.The operation of the indicators 955-959 is the same as has previouslybeen described, namely, the LED indicators 955-959 blink when theswitches 941-944 are turned on but the lighting subsystems 951-954 arenot turned on. As the subsystems 951-954 turn on one by one, so too dothe LED indicators 955-959. Accordingly, because the operation of theLED indicators 955-959 indicators is the same as has been describedelsewhere, the operation of the LED indicators 955-959 will not bedescribed further.

At step 1006, the central control unit generates first, second, third,fourth and fourth control signals. At step 1007, the central controlunit 14 transmits the first control signal in the form of a networkmessage to the interface module 35. At step 1008, the interface module35 transmits the first control signal in the form of a power signal tothe first emergency lighting subsystem 951.

The control unit 14 then transmits additional control signals atone-half second intervals. Thus, after a one-half second delay at step1009, the central control unit transmits the second control signal inthe form a network message to the interface module 31 at step 1010. Atstep 1011, the interface module 31 then sends the second control signalin the form of a power signal to the second emergency lighting subsystem952. After another one-half second delay at step 1012, the centralcontrol unit 14 transmits the third control signal in the form a networkmessage to the interface module 34 at step 1013. At step 1014, theinterface module 34 then sends the third control signal in the form of apower signal to the third emergency lighting subsystem 953. Finally,after another one-half second delay at step 1015, the central controlunit 14 transmits the third control signal in the form a network messageto the interface module 35 at step 1016. At step 1017, the interfacemodule 35 then sends the second control signal in the form of a powersignal to the fourth emergency lighting subsystem 954. As previouslyindicated in connection with step 510 of FIG. 5, there are a variety ofways in which the blinking/flashing of outputs can be achieved, usingeither only a single control signal or using a first control signalfollowed by multiple additional control signals.

Referring now to FIGS. 11A and 11B, another advantage of the controlsystem 12 is the flexibility of the load sequencer 916. Like the loadmanager 616, the load sequencer 916 can operate as a function of theoperating mode of the fire truck. Thus, in FIG. 11A, the load sequencer916 turns subsystems on in a first order (1st, 2nd, 3rd, 4th, 5th, 6th)in a first operating mode of the fire truck 10. In a different operatingmode of the fire truck, a somewhat different group of subsystems is loadsequenced and they are load sequenced in a different order (3rd, 1st,5th, 4th, 7th, 8th). The two different modes of operation can beactivated, for example by two different master on/off switches. In thecontext of emergency lighting systems, this arrangement is useful whereit is desirable to have the emergency lighting subsystems load sequencedifferently depending on whether the fire truck is traveling from thefire station to the fire or vice versa.

As another example of load sequencing performed as a function of theoperating mode of the truck, it may be noted that, because the controlunit 14 knows the on/off states of all of the output devices 50, loadsequencing can be performed taking into account the current on/off stateof the output devices that are load sequenced. For example, if someoutput devices are already turned on, then the load sequencer 916 canimmediately proceed to the next output device without wasting timeturning on a device that is already turned on. This advantageouslypermits load sequencing to be performed more quickly.

3. Aerial Control

Referring now to FIG. 12, a preferred embodiment of a fire truck 1210with an aerial 1211 having an aerial control system 1212 is illustrated.By way of overview, the control system 1212 comprises an aerial centralcontrol unit 1214, a plurality of microprocessor-based interface modules1220, 1230 and 1235, a plurality of input devices 1240, and a pluralityof output devices 1250. The central control unit 1214 and the interfacemodules 1220, 1230 and 1235 are connected to each other by acommunication network 1260.

The control system 1212 is similar in most respect to the control system12, with the primary difference being that the control system 1212 isused to control the output devices 1250 on the aerial 1211 based oninput status information from the input devices 1240, rather than tocontrol the output devices 50 on the chassis 11. The interface modules1220 and 1230 may be identical to the interface modules 20 and 30,respectively, and the central control unit 1214 may be identical to thecentral control unit 14 except that a different control program isrequired in connection with the aerial 1211. Accordingly, the discussionabove regarding the interconnection and operation of the interfacemodules 20 and 30 with the input devices 40 and output devices 50applies equally to the central control unit 1214, except to the extentthat the control system 1212 is associated with the aerial 1211 and notwith the chassis 11.

The aerial control system 1212 also includes the interface modules1225-1227, which are similar to the interface modules 20 and 30 exceptthat different I/O counts are utilized. In the preferred embodiment, theinterface modules 1225-1227 have twenty-eight switch inputs (two ofwhich are configurable as frequency inputs). As previously noted, ratherthan using several different types of interface modules, it may bedesirable to use only a single type of interface module in order toreduce inventory requirements. Additionally, the number of interfacemodules and the I/O counts are simply one example of a configurationthat may be utilized.

It is desirable to use a control system 1212 for the aerial 1211 whichis separate from the control system 12 in order to provide a clearseparation of function between systems associated with the aerial 1211and systems associated with the chassis 11. Additionally, as a practicalmatter, many fire trucks are sold without aerials and thereforeproviding a separate aerial control system enables a higher levelcommonality with respect to fire trucks that have aerials and firetrucks that do not have aerials.

A specific example will now be given of a preferred interconnection ofthe interface modules with a plurality of input devices 1240 and outputdevices 1250. The interface module 1221 receives inputs from switches1241 a which may include for example an aerial master switch thatactivates aerial electrical circuits, an aerial PTO switch thatactivates the transmission to provide rotational input power for thehydraulic pump, and a platform leveling switch that momentarilyactivates a platform (basket) level electrical circuit to level thebasket relative to the current ground grade condition. The LEDindicators 1251 provide visual feedback regarding the status of theinput switches 1241 a.

The interface modules 1225 and 1231 are located near a ground-levelcontrol station at a rear of the fire truck 10. The interface modules1225 and 1231 receive inputs from switches 1242 a and 1243 a thatinclude, for example, an auto level switch that activates a circuit tolevel the fire truck using the stabilizer jacks and an override switchthat overrides circuits for emergency operation. The interface modules1225 and 1231 may also receive inputs from an operator panel such as astabilizer control panel 1242 b, which includes switches that controlthe raising and lowering of front and rear stabilizer jacks, and theextending and retracting of front and rear stabilizer jacks. Thestabilizer is an outrigger system which is deployed to prevent the firetruck from becoming unstable due to the deployment of an aerial system(e.g., an eighty-five foot extendable ladder). The interface module 1231may drive outputs that are used to control deployment the stabilizer,which can be deployed anywhere between zero and five feet.

The interface modules 1226 and 1232 are located near a turn table 1218at the rear of the fire truck 10. The interface modules may receiveinputs from switches and sensors 1244 a and 1245 a, as well as switchesthat are part of an aerial control panel 1245 b and are used to controlthe extension/retraction, raising/lowering, and rotation of the aerial1211. The interface modules 1226 and 1232 drive outputs that control theextension/retraction, raising/lowering, and rotation of the aerial 1211,as well as LED indicators 1254 b that provide operator feedbackregarding the positions of switches and other I/O status information.The interface modules 1227 and 1233 are located in the basket of theaerial and provide duplicate control for the extension/retraction,raising/lowering, and rotation of the aerial.

Additional inputs and outputs 1251 b may be used to establish acommunication link between the control system 12 and the control system1212. In other words, the digital on/off outputs of one control systemcan be connected to the switch inputs of the other control system, andvice versa. This provides for a mechanism of transferring I/O statusinformation back and forth between the two control systems 12 and 1212.

The control system 1212 has complete motion control of the aerial 1211.To this end, the control program 1216 includes an envelope motioncontroller 1216 a, load motion controller 1216 b and interlockcontroller 1216 c. Envelope motion control refers to monitoring theposition of the aerial and preventing the aerial from colliding with theremainder of the fire truck 10, and otherwise preventing undesirableengagement of mechanical structures on the fire truck due to movement ofthe aerial. Envelope motion control is implemented based on the knowndimensions of the aerial 1211 and the known dimensions and position ofother fire truck structures relative to the aerial 1211 (e.g., theposition and size of the cab 17 relative to the aerial 1211) and theposition of the aerial 1211 (which is measured with feedback sensors1244 a and 1245 a). The control system 1212 then disallows inputs thatwould cause the undesirable engagement of the aerial 1211 with otherfire truck structures.

Load motion control refers to preventing the aerial from extending sofar that the fire truck tips over due to unbalanced loading. Load motioncontrol is implemented by using an appropriate sensor to measure thetorque placed on the cylinder that mechanically couples the aerial 1211to the remainder of the fire truck. Based on the torque and the knownweight of the fire truck, it is determined when the fire truck is closeto tipping, and warnings are provided to the operator by way of textmessages and LED indicators.

Interlock control refers to implementing interlocks for aerial systems.For example, an interlock may be provided that require the parking brakebe engaged before allowing the aerial to move, that require thestabilizers to be extended and set before moving the aerial 1211, thatrequire that the aerial PTO be engaged before attempting to move theaerial, and so on.

Advantageously, therefore, the control system makes the operation of theaerial much safer. For example, with respect to load motion control, thecontrol system 1212 automatically alerts firefighters if the extensionof the aerial is close to causing the fire truck to tip over. Factorssuch as the number and weight of people in the basket 1219, the amountand weight of equipment in the basket 1219, the extent to which thestabilizers are deployed, whether and to what extent water is flowingthrough aerial hoses, and so on, are taken into account automatically bythe torque sensors associated with the cylinder that mounts the aerialto the fire truck. This eliminates the need for a firefighter to have tomonitor these conditions manually, and makes it possible for the controlsystem 1212 to alert an aerial operator to unsafe conditions, and putsless reliance on the operator to make sure that the aerial is operatingunder safe conditions.

4. Additional Aspects

From the foregoing description, a number advantages of the preferredfire truck control system are apparent. In general, the control systemis easier to use, more flexible, more robust, and more reliable thanexisting fire truck control systems. In addition, because of theseadvantages, the control system also increases firefighter safety becausethe many of the functions that were previously performed by firefightersare performed automatically, and the control system also makes possiblefeatures that would otherwise be impossible or at least impractical.Therefore, firefighters are freed to focus on fighting fires.

The control system is easier to use because the control system providesa high level of cooperation between various vehicle subsystems. Thecontrol system can keep track of the mode of operation of the firetruck, and can control output devices based on the mode of operation.The functions that are performed on the fire truck are more fullyintegrated to provide a seamless control system, resulting in betterperformance.

For example, features such as load management and load sequencing areimplemented in the control program executed by the central control unit.No additional hardware is required to implement load management and loadsequencing. Therefore, if it is desired to change the order of loadsequencing, all that is required is to modify the control program. It isalso possible to have different load sequencing defined for differentmodes of operation of the vehicle with little or no increase inhardware. The manner in which load management is performed can also bechanged dynamically during the operation of the fire truck.

The control system is robust and can accept almost any new featurewithout changes in wiring. Switches are connected to a central controlunit and not to outputs directly, and new features can be programmedinto the control program executed by the central control unit. A systemcan be modified by adding a new switch to an existing interface module,or by modifying the function of an existing switch in the controlprogram. Therefore, modifying a system that is already in use is easybecause little or no wiring changes are required.

Additionally, because the control system has access to input statusinformation from most or all of the input devices on the fire truck andhas control over most or all of the output devices on the fire truck, ahigh level of cooperation between the various subsystems on the firetruck is possible. Features that require the cooperation of multiplesubsystems are much easier to implement.

The fire truck is also easier to operate because there is improvedoperator feedback. Displays are provided which can be used to determinethe I/O status of any piece of equipment on the vehicle, regardless ofthe location of the display. Additionally, the displays facilitatetroubleshooting, because troubleshooting can be performed in real timeat the scene of a fire when a problem is occurring. Troubleshooting isalso facilitated by the fact that the displays are useable to displayall of the I/O status information on the fire truck. There is no needfor a firefighter to go to different locations on the fire truck toobtain required information. Troubleshooting is also facilitated by theprovision of a central control unit which can be connected by modem toanother computer. This allows the manufacturer to troubleshoot the firetruck as soon as problems arise.

LED indicators associated with switches also improve operator feedback.The LEDs indicate whether the switch is considered to be off or on, orwhether the switch is considered to be on but the output devicecontrolled by the switch is nevertheless off due to some other conditionon the fire truck.

Because the control system is easier to use, firefighter safety isenhanced. When a firefighter is fighting fires, the firefighter is ableto more fully concentrate on fighting the fire and less on having toworry about the fire truck. To the extent that the control systemaccomplishes tasks that otherwise would have to be performed by thefirefighter, this frees the firefighter to fight fires.

The control system is also more reliable and maintainable, in partbecause relay logic is replaced with logic implemented in a controlprogram. The logic in the control program is much easier totroubleshoot, and troubleshooting can even occur remotely by modem. Alsomechanical circuit breakers can be replaced with electronic control,thereby further reducing the number of mechanical failure points andmaking current control occur more seamlessly. The simplicity of thecontrol system minimizes the number of potential failure points andtherefore enhances reliability and maintainability.

The system is also more reliable and more maintainable because there isless wire. Wiring is utilized only to established dedicated linksbetween input/output devices and the interface module to which they areconnected. The control system uses distributed power distribution anddata collecting. The interface modules are interconnected by a networkcommunication link instead of a hardwired link, thereby reducing theamount of wiring on the fire truck. Most wiring is localized wiringbetween the I/O devices and a particular interface module.

Additionally, the interface modules are interchangeable units. In thedisclosed embodiment, the interface modules 20 are interchangeable witheach other, and the interface modules 30 are interchangeable with eachother. If a greater degree of interchangeability is required, it is alsopossible to use only a single type of interface module. If the controlsystem were also applied to other types of equipment service vehicles(e.g., snow removal vehicles, refuse handling vehicles, cement/concretemixers, military vehicles such as those of the multipurpose modulartype, on/off road severe duty equipment service vehicles, and so on),the interface modules would even be made interchangeable acrossplatforms since each interface module views the outside world in termsof generic inputs and outputs, at least until configured by the centralcontrol unit. Because the interface modules are interchangeable,maintainability is enhanced. An interface module that begins tomalfunction due to component defects may be replaced more easily. Onpower up, the central control unit downloads configuration informationto the new interface module, and the interface module becomes fullyoperational. This enhances the maintainability of the control system.

Because the interface modules are microprocessor-based, the amount ofprocessing required by the central control unit as well as the amount ofcommunication that is necessary between the interface modules and thecentral control unit is reduced. The interface modules performpreprocessing of input signals and filter out less critical inputsignals and, as a result, the central control unit receives and respondsto critical messages more quickly.

B. Military Vehicle Control System

Referring now to FIG. 14, a preferred embodiment of a military vehicle1410 having a control system 1412 is illustrated. As previouslyindicated, the control system described above can be applied to othertypes of equipment service vehicles, such as military vehicles, becausethe interface modules view the outside world in terms of generic inputsand outputs. Most or all of the advantages described above in thecontext of fire fighting vehicles are also applicable to militaryvehicles. As previously described, however, it is sometimes desirable inthe context of military applications for the military vehicle controlsystem to be able to operate at a maximum level of effectiveness whenthe vehicle is damaged by enemy fire, nearby explosions, and so on. Inthis situation, the control system 1412 preferably incorporates a numberof additional features, discussed below, that increase the effectivenessof the control system 1412 in these military applications.

By way of overview, the control system 1412 comprises a plurality ofmicroprocessor-based interface modules 1420, a plurality of input andoutput devices 1440 and 1450 (see FIG. 15) that are connected to theinterface modules 1420, and a communication network 1460 thatinterconnects the interface modules 1420. The control system 1412preferably operates in the same manner as the control system 12 of FIGS.1-13, except to the extent that differences are outlined are below. Aprimary difference between the control system 12 and the control system1412 is that the control system 1412 does not include a central controlunit that is implemented by a single device fixed at one location.Rather, the control system 1412 includes a central control unit that isallowed to move from location to location by designating one of theinterface modules 1420 as a “master” interface module and by furtherallowing the particular interface module that is the designated masterinterface module to change in response to system conditions. As will bedetailed below, this feature allows the control system 1412 to operateat a maximum level of effectiveness when the military vehicle 1410 isdamaged. Additional features that assist failure management are alsoincluded.

More specifically, in the illustrated embodiment, the control system1412 is used in connection with a military vehicle 1410 which is amultipurpose modular military vehicle. As is known, a multipurposemodule vehicle comprises a chassis and a variant module that is capableof being mounted on the chassis, removed, and replaced with anothervariant module, thereby allowing the same chassis to be used fordifferent types of vehicles with different types of functionalitydepending on which variant module is mounted to the chassis. In theillustrated embodiment, the military vehicle 1410 is a wrecker andincludes a wrecker variant module 1413 mounted on a chassis (underbody)1417 of the military vehicle 1410. The weight of the variant module 1413is supported by the chassis 1417. The variant module 1413 includes amechanical drive device 1414 capable of imparting motion to solid orliquid matter that is not part of the military vehicle 1410 to providethe military vehicle 1410 with a particular type of functionality. InFIG. 14, where the variant module 1413 is a wrecker variant, themechanical drive device is capable of imparting motion to a towedvehicle. As shown in FIG. 20, the variant module 1413 is removable andreplaceable with other types of variant modules, which may include adump truck variant 1418 a, a water pump variant 1418 b, a telephonevariant 1418 c, and so on. Thus, for example, the wrecker variant 1413may be removed and replaced with a water pump variant 1418 b having adifferent type of drive mechanism (a water pump) to provide a differenttype of functionality (pumper functionality). The I/O devices 1440 and1450 used by the vehicle 1410 include devices that are the same as orsimilar to the non-fire truck specific I/O devices of FIGS. 1-13 (i.e.,those types of I/O devices that are generic to most types of vehicles),as well as I/O devices that are typically found on the specific type ofvariant module chosen (in FIG. 14, a wrecker variant).

The interface modules 1420 are constructed in generally the same manneras the interface modules 20 and 30 and each include a plurality ofanalog and digital inputs and outputs. The number and type of inputs andoutputs may be the same, for example, as the vehicle interface modules30. Preferably, as described in greater detail below, only a single typeof interface module is utilized in order to increase the fieldserviceability of the control system 1412. Herein, the reference numeral1420 is used to refer to the interface modules 1420 collectively,whereas the reference numerals 1421-1430 are used to refer to specificones of the interface modules 1420. The interface modules are describedin greater detail in connection with FIGS. 15-18.

Also connected to the communication network 1460 are a plurality ofdisplays 1481 and 1482 and a data logger 1485. The displays 1481 and1482 permit any of the data collected by the control system 1412 to bedisplayed in real time, and also display warning messages. The displays1481 and 1482 also include membrane pushbuttons that allow the operatorsto scroll through, page through, or otherwise view the screens of datathat are available. The membrane pushbuttons may also allow operators tochange values of parameters in the control system 1412. The data logger1485 is used to store information regarding the operation of themilitary vehicle 1410. The data logger 1485 may also be used as a “blackbox recorder” to store information logged during a predetermined amountof time (e.g., thirty seconds) immediately prior to the occurrence ofone or more trigger events (e.g., events indicating that the militaryvehicle 1410 has been damaged or rendered inoperative, such as when anoperational parameter such as an accelerometer threshold has beenexceeded).

Finally, FIG. 14 shows an engine system including an engine 1492 and anengine control system 1491, a transmission system including atransmission 1493 and a transmission control system 1494, and ananti-lock brake system including an anti-lock brake control system 1495.These systems may be interconnected with the control system 1412 ingenerally the same manner as discussed above in connection with theengine 92, the engine control system 91, the transmission 93, thetransmission control system 94, and the anti-lock brake system 36 ofFIG. 1.

Referring now also to FIG. 15-18, the structure and interconnection ofthe interface modules 1420 is described in greater detail. Referringfirst to FIG. 15, the interconnection of the interface modules 1420 witha power source 1500 is described. The interface modules 1420 receivepower from the power source 1500 by way of a power transmission link1502. The interface modules 1420 are distributed throughout the militaryvehicle 1410, with some of the interface modules 1420 being located onthe chassis 1417 and some of the interface modules 1420 being located onthe variant module 1413.

The control system is subdivided into three control systems including achassis control system 1511, a variant control system 1512, and anauxiliary control system 1513. The chassis control system 1511 includesthe interface modules 1421-1425 and the I/O devices 1441 and 1451, whichare all mounted on the chassis 1417. The variant control system 1512includes the interface modules 1426-1428 and the I/O devices 1442 and1452, which are all mounted on the variant module 1413. The auxiliarycontrol system 1513 includes the interface modules 1429-1430 and the I/Odevices 1443 and 1453, which may be mounted on either the chassis 1417or the variant module 1413 or both.

The auxiliary control system 1513 may, for example, be used to control asubsystem that is disposed on the variant module but that is likely tobe the same or similar for all variant modules (e.g., a lightingsubsystem that includes headlights, tail lights, brake lights, andblinkers). The inclusion of interface modules 1420 within a particularcontrol system may also be performed based on location rather thanfunctionality. For example, if the variant module 1413 has an aerialdevice, it may be desirable to have one control system for the chassis,one control system for the aerial device, and one control system for theremainder of the variant module. Additionally, although each interfacemodule 1420 is shown as being associated with only one of the controlsystems 1511-1513, it is possible to have interface modules that areassociated with more than one control system. It should also be notedthat the number of sub-control systems, as well as the number ofinterface modules, is likely to vary depending on the application. Forexample, a mobile command vehicle is likely to have more controlsubsystems than a wrecker variant, given the large number of I/O devicesusually found on mobile command vehicles.

The power transmission link 1502 may comprise a single power line thatis routed throughout the military vehicle 1410 to each of the interfacemodules 1420, but preferably comprises redundant power lines. Again, inorder to minimize wiring, the interface modules 1420 are placed so as tobe located as closely as possible to the input devices 1440 from whichinput status information is received and the output devices 1450 thatare controlled. This arrangement allows the previously-describedadvantages associated with distributed data collection and powerdistribution to be achieved. Dedicated communication links, which mayfor example be electric or photonic links, connect the interface modules1421-1430 modules with respective ones of the I/O devices, as previouslydescribed.

Referring next to FIG. 16, the interconnection of the interface modules1420 by way of the communication network 1460 is illustrated. Aspreviously indicated, the control system 1412 is subdivided into threecontrol systems 1511, 1512 and 1513. In accordance with thisarrangement, the communication network 1460 is likewise furthersubdivided into three communication networks 1661, 1662, and 1663. Thecommunication network 1661 is associated with the chassis control system1511 and interconnects the interface modules 1421-1425. Thecommunication network 1662 is associated with the variant control system1512 and interconnects the interface modules 1426-1428. Thecommunication network 1663 is associated with the auxiliary controlsystem 1513 and interconnects the interface modules 1429-1430.Communication between the control systems 1511-1513 occurs by way ofinterface modules that are connected to multiple ones of the networks1661-1663. Advantageously, this arrangement also allows the interfacemodules to reconfigure themselves to communicate over another network inthe event that part or all of their primary network is lost. Forexample, in FIG. 17A, when a portion of the communication network 1663is lost, the interface module 1429 reconfigures itself to communicatewith the interface module 1430 by way of the communication network 1662and the interface module 1427.

In practice, each of the communication networks 1661-1663 may be formedof two or more communication networks to provide redundancy within eachcontrol system. Indeed, the connection of the various interface modules1420 with different networks can be as complicated as necessary toobtain the desired level of redundancy. For simplicity, these potentialadditional levels of redundancy will be ignored in the discussion ofFIG. 16 contained herein.

The communication networks 1661-1663 may be implemented in accordancewith SAE J1708/1587 and/or J1939 standards, or some other networkprotocol, as previously described. The transmission medium is preferablyfiber optic cable in order to reduce the amount of electromagneticradiation that the military vehicle 1410 produces, therefore making thevehicle less detectable by the enemy. Fiber optic networks are also morerobust to the extent that a severed fiber optic cable is still usable tocreate two independent networks, at least with reduced functionality.

When the variant module 1413 is mounted on the chassis 1417, connectingthe chassis control system 1511 and the variant control system 1512 isachieved simply through the use of two mating connectors 1681 and 1682that include connections for one or more communication busses, power andground. The chassis connector 1682 is also physically and functionallymateable with connectors for other variant modules, i.e., the chassisconnector and the other variant connectors are not only capable ofmating physically, but the mating also produces a workable vehiclesystem. A given set of switches or other control devices 1651 on thedash (see FIG. 14) may then operate differently depending on whichvariant is connected to the chassis. Advantageously, therefore, it ispossible to provide a single interface between the chassis and thevariant module (although multiple interfaces may also be provided forredundancy). This avoids the need for a separate connector on thechassis for each different type of variant module, along with theadditional unutilized hardware and wiring, as has conventionally beenthe approach utilized.

Upon power up, the variant control system 1512 and the chassis controlsystem 1511 exchange information that is of interest to each other. Forexample, the variant control system 1512 may communicate the varianttype of the variant module 1413. Other parameters may also becommunicated. For example, information about the weight distribution onthe variant module 1413 may be passed along to the chassis controlsystem 1511, so that the transmission shift schedule of the transmission1493 can be adjusted in accordance with the weight of the variant module1413, and so that a central tire inflation system can control theinflation of tires as a function of the weight distribution of thevariant. Similarly, information about the chassis can be passed along tothe variant. For example, where a variant module is capable of beingused by multiple chassis with different engine sizes, engine informationcan be communicated to a wrecker variant module so that the wreckervariant knows how much weight the chassis is capable of pulling. Thus,an initial exchange of information in this manner allows the operationof the chassis control system 1511 to be optimized in accordance withparameters of the variant module 1413, and vice versa.

It may also be noted that the advantages obtained for military variantscan also be realized in connection with commercial variants. Thus, ablower module, a sweeper module, and a plow module could be provided forthe same chassis. This would allow the chassis to be used for a sweeperin summer and a snow blower or snow plow in winter.

As shown in FIG. 16, each control system 1511-1513 includes an interfacemodule that is designated “master” and another that is designated“deputy master.” Thus, for example, the chassis control system 1511includes a master interface module 1423 and a deputy master interfacemodule 1422. Additional tiers of mastership may also be implemented inconnection with the interface modules 1421, 1424 and 1425.

The interface modules 1420 are assigned their respective ranks in thetiers of mastership based on their respective locations on the militaryvehicle 1410. A harness connector at each respective location of themilitary vehicle 1410 connects a respective one of the interface modules1420 to the remainder of the control system 1412. The harness connectoris electronically keyed, such that being connected to a particularharness connector provides an interface module 1420 with a uniqueidentification code or address M. For simplicity, the value M is assumedto be a value between 1 and N, where N is the total number of interfacemodules on the vehicle (M=10 in the illustrated embodiment).

The interface modules 1420 each store configuration information that,among other things, relates particular network addresses with particularranks of mastership. Thus, for example, when the interface module 1423boots up, it ascertains its own network address and, based on itsnetwork address, ascertains that it is the master of the control system1511. The interface module 1423 serves as the central control unit solong as the interface module 1423 is competent to do so. As shown inFIG. 17B, if it is determined that the interface module 1423 is nolonger competent to serve as master (e.g., because the interface module1423 has been damaged in combat), then the interface module 1422 becomesthe master interface module and begins serving as the central controlunit. This decision can be made, for example, by the interface module1423 itself, based on a vote taken by the remaining interface modules1420, or based on a decision by the deputy master.

Referring next to FIG. 18, an exemplary one of the interface modules1420 is shown in greater detail. The interface modules 1420 each includea microprocessor 1815 that is sufficiently powerful to allow eachinterface module to serve as the central control unit. The interfacemodules are identically programmed and each include a memory 1831 thatfurther includes a program memory 1832 and a data memory 1834. Theprogram memory 1832 includes BIOS (basic input/output system) firmware1836, an operating system 1838, and application programs 1840, 1842 and1844. The application programs include a chassis control program 1840,one or more variant control programs 1842, and an auxiliary controlprogram 1844. The data memory 1834 includes configuration information1846 and I/O status information 1848 for all of the modules 1420-1430associated with the chassis 1417 and its variant module 1413, as well asconfiguration information for the interface modules (N+1 to Z in FIG.18) of other variant modules that are capable of being mounted to thechassis 1417.

It is therefore seen that all of the interface modules 1420 that areused on the chassis 1417 and its variant module 1413, as well as theinterface modules 1420 of other variant modules that are capable ofbeing mounted to the chassis 1417, are identically programmed andcontain the same information. Each interface module 1420 then utilizesits network address to decide when booting up which configurationinformation to utilize when configuring itself, and which portions ofthe application programs 1840-1844 to execute given its status as amaster or non-master member of one of the control systems 1511-1513. Theinterface modules are both physically and functionally interchangeablebecause the interface modules are capable of being plugged in at anyslot on the network, and are capable of performing any functions thatare required at that slot on the network.

This arrangement is highly advantageous. Because all of the interfacemodules 1420 are identically programmed and store the same information,the interface modules are physically and functionally interchangeablewithin a given class of vehicles. Thus, if an interface module 1420 onone variant module is rendered inoperative, but the variant module isotherwise operational, the inoperative interface module can be replacedwith an interface module scavenged from another inoperative vehicle.When the replacement interface module 1420 reboots, it will thenreconfigure itself for use in the new vehicle, and begin operating thecorrect portions of the application programs 1840-1844. This is the caseeven when the two vehicles are different types of vehicles.

Additionally, if a highly critical interface module is renderedinoperable, the highly critical interface module can be swapped with aninterface module that is less critical. Although the input/outputdevices associated with the less critical interface module will nolonger be operable, the input/output devices associated with the morecritical interface module will be operable. This allows theeffectiveness of the military vehicle to be maximized by allowingundamaged interface modules to be utilized in the most optimal manner.In this way, the field serviceability of the control system 1412 isdramatically improved. Further, the field serviceability of the controlsystem 1412 is also improved by the fact that only a single type ofinterface module is used, because the use of a single type of interfacemodule makes it easier to find replacement interface modules.

Additionally, as previously noted, each interface module 1420 stores I/Ostatus information for all of the modules 1420-1430 associated with thechassis 1417 and its variant module 1413. Therefore, each interfacemodule 1420 has total system awareness. As a result, it is possible tohave each interface module 1420 process its own inputs and outputs basedon the I/O status information in order to increase system responsivenessand in order to reduce the amount of communication that is required withthe central control unit. The main management responsibility of thecentral control unit or master interface module above and beyond theresponsibilities of all the other interface modules 1420 then becomes,for example, to provide a nexus for interface operations with devicesthat are external to the control system of which the central controlunit is a part.

Referring now to FIG. 19, FIG. 19 is a truth table that describes theoperation of the control system 1412 in the event of failure of one ofthe interface modules 1420 and/or one of the input devices 1440. Thearrangement shown in FIG. 19 allows the control system 1412 to be ableto continue to operate in the event of failure using a “best guess”method of controlling outputs.

In the example of FIG. 19, two output devices are controlled based ontwo input devices. For example, the first output device may beheadlights of the military vehicle 1410, the first input device may be acombat switch or combat override switch that places the entire vehicleinto a combat mode of operation, and the second input may be an operatorswitch for operator control of the headlights. The second output deviceis discussed further below. For simplicity, only the input states of twobinary input devices are shown. In practice, of course, the controllogic for most output devices will usually be a function of more inputdevices, in some cases ten or more input devices including analog inputdevices. Nevertheless, the simplified truth table of FIG. 19 issufficient to obtain an understanding of this preferred aspect of theinvention.

The truth table of FIG. 19 shows a number of different possible inputstates and the corresponding output states. In the first two states,when the combat override switch (input #1) is off, then the headlights(output #1) are controlled as a function of the operator switch. Thus,if the operator switch is on, then the control system 1412 turns theheadlights on, and if the operator switch is off, then the controlsystem 1412 turns the headlights off. In the third and fourth inputstates, the combat override switch is on, and therefore the controlsystem 1412 turns the headlights off in order to make the vehicle lessdetectable by the enemy. It may be noted that the control system 1412ignores the input state of the second input device when the combatoverride switch is on. The third column in the truth table couldtherefore instead be the output of a safety interlock, since safetyinterlocks are another example of input information that is sometimesignored when a combat override is turned on. This would allow thecontrol system 1412 to take into account the urgency of a combatsituation while still also implementing safety functions to the extentthat they do not interfere with the operation of the vehicle 1410.

The truth table also has a number of additional states (five throughnine) corresponding to situations in which one or both of the inputs isdesignated as undetermined (“?” in FIG. 19). Thus, for example, instates five and six, the input state of the operator switch (input #2)is designated as undetermined. The undetermined state of the operatorswitch may be the result of the failure of the interface module thatreceives the input signal from the operator switch, a failure of theelectrical connection between the switch and the interface module,and/or a failure of the operator switch itself. In the fifth state, whenthe combat override switch is off and the state of the operator switchis undetermined, the control system 1412 turns on the headlights, basedon the assumption that if it is nighttime the operator wants the lightson and if it is daytime the operator does not have a strong preferenceeither way. In the sixth state, when the combat override switch is onand the state of the operator switch is undetermined, the control system1412 turns off the headlights, because the headlights should always beturned off in the combat mode of operation.

In states seven through nine, the input state of the combat overrideswitch (input #1) is designated as undetermined. The undetermined stateof the combat override switch may be caused by generally the samefactors that are liable to cause the state of the operator switch to beundetermined. In all of these states, the control system 1412 turns offthe headlights, based on the worst case assumption that the militaryvehicle may be in combat and that therefore the headlights should beturned off.

The arrangement shown in FIG. 19 is thus applied to all output devices1450 on the military vehicle. In this way, the control logic forcontrolling the output devices is expanded to take into account a third“undetermined” state for each of the input devices, and an entireadditional layer of failure management is added to the control logic. Inthis way, the control system 1412 is able to remain operational (atleast in a best guess mode) when the input states of one or more inputdevices cannot be determined. This prevents output devices that have anoutput state based on the input state of a given input device from beingcrippled when a system failure causes one or more input devices to belost.

This arrangement also allows the output state of each output device tobe programmed individually in failure situations. In other words, when agiven input device is lost, the control system can be programmed toassume for purposes of some output devices (using the above describedtruth table arrangement) that the input device is on and to assume forthe purposes of other output devices that the input device is off. Forexample, in FIG. 19, if output device #2 is another output device thatis controlled by the same operator switch, the control system can beprogrammed to assume for purposes of output device #2 that the operatorswitch is off in state five rather than on, such that the control systemturns off the output device #2 in state five. In this way, it is notnecessary to assume the same input state for purposes of all outputdevices.

It may also be noted that military vehicles tend to make widespread useof redundant sensors. In this case, by connecting the redundant sensorsto different ones of the interface modules, the state table for eachoutput device can be modified to accept either input, thereby making itpossible for the control system 1412 to obtain the same information by adifferent route. Further, if the redundant sensors disagree on the inputstatus of a system parameter, then this disagreement itself can betreated as an undetermined input state of an input device. In this way,rather than using a voting procedure in which the sensors vote on thestate of the input device for purposes of all output devices, theuncertainty can be taken into account and best guess decisions regardinghow to operate can be made for each of the various output devicesindividually.

As previously described, each interface module 1420 has total systemawareness. Specifically, the data memory 1834 of each interface module1420 stores I/O status information 1848 for not only local I/O devices1440 and 1450 but also for non-local I/O devices 1440 and 1450 connectedto remaining ones of the interface modules 1420. Referring now to FIGS.21-24, a preferred technique for transmitting I/O status informationbetween the interface modules 1420 will now be described. Although thistechnique is primarily described in connection with the chassis controlsystem 1511, this technique is preferably also applied to the variantcontrol system 1512 and the auxiliary control system 1513, and/or in thecontrol system 12.

Referring first to FIG. 21, as previously described, the chassis controlsystem 1511 includes the interface modules 1421-1425, the input devices1441, and the output devices 1451. Also shown in FIG. 21 are the display1481, the data logger 1485, and the communication network 1661 whichconnects the interface modules 1421-1425. In practice, the system mayinclude additional devices, such as a plurality of switch interfacemodules connected to additional I/O devices, which for simplicity arenot shown. The switch interface modules may be the same as the switchinterface modules 20 previously described and, for example, may beprovided in the form of a separate enclosed unit or in the more simpleform of a circuit board mounted with associated switches and low poweroutput devices. In practice, the system may include other systems, suchas a display interface used to drive one or more analog displays (suchas gauges) using data received from the communication network 1661. Anyadditional modules that interface with I/O devices preferably broadcastand receive I/O status information and exert local control in the samemanner as detailed below in connection with the interface modules1421-1425. As previously noted, one or more additional communicationnetworks may also be included which are preferably implemented inaccordance with SAE J1708/1587 and/or J1339 standards. The communicationnetworks may be used, for example, to receive I/O status informationfrom other vehicle systems, such as an engine or transmission controlsystem. Arbitration of I/O status broadcasts between the communicationnetworks can be performed by one of the interface modules 1420.

To facilitate description, the input devices 1441 and the output devices1451 have been further subdivided and more specifically labeled in FIG.21. Thus, the subset of the input devices 1441 which are connected tothe interface module 1421 are collectively labeled with the referencenumeral 1541 and are individually labeled as having respective inputstates I-11 to I-15. Similarly, the subset of the output devices 1451which are connected to the interface module 1421 are collectivelylabeled with the reference numeral 1551 and are individually labeled ashaving respective output states O-11 to O-15. A similar pattern has beenfollowed for the interface modules 1422-1425, as summarized in Table Ibelow: TABLE I Interface Input Output Module Devices Input StatesDevices Output States 1421 1541 I-11 to I-15 1551 O-11 to O-15 1422 1542I-21 to I-25 1552 O-21 to O-25 1423 1543 I-31 to I-35 1553 O-31 to O-351424 1544 I-41 to I-45 1554 O-41 to O-45 1425 1545 I-51 to I-55 1555O-51 to O-55

Of course, although five input devices 1441 and five output devices 1451are connected to each of the interface modules 1420 in the illustratedembodiment, this number of I/O devices is merely exemplary and adifferent number of devices could also be used, as previously described.

The interface modules 1420 each comprise a respective I/O status table1520 that stores information pertaining to the I/O states of the inputand output devices 1441 and 1451. Referring now to FIG. 22, an exemplaryone of the I/O status tables 1520 is shown. As shown in FIG. 22, the I/Ostatus table 1520 stores I/O status information pertaining to each ofthe input states I-11 to I-15, I-21 to I-25, I-31 to I-35, I-41 to I-45,and I-51 to I-55 of the input devices 154I-1545, respectively, and alsostores I/O status information pertaining to each of the output statesO-11 to O-15, O-21 to O-25, O-31 to O-35, O-41 to O-45, and O-51 to O-55of the output devices 155I-1555, respectively. The I/O status tables1520 are assumed to be identical, however, each I/O status table 1520 isindividually maintained and updated by the corresponding interfacemodule 1420. Therefore, temporary differences may exist between the I/Ostatus tables 1520 as updated I/O status information is received andstored. Although not shown, the I/O status table 1520 also stores I/Ostatus information for the interface modules 1426-1428 of the variantcontrol system 1512 and the interface modules 1429-1430 of the auxiliarycontrol system 1513.

In practice, although FIG. 22 shows the I/O status information beingstored next to each other, the memory locations that store the I/Ostatus information need not be contiguous and need not be located in thesame physical media. It may also be noted that the I/O status table 1520is, in practice, implemented such that different I/O states are storedusing different amounts of memory. For example, some locations store asingle bit of information (as in the case of a digital input device ordigital output device) and other locations store multiple bits ofinformation (as in the case of an analog input device or an analogoutput device). The manner in which the I/O status table is implementedis dependent on the programming language used and on the different datastructures available within the programming language that is used. Ingeneral, the term I/O status table is broadly used herein to encompassany group of memory locations that are useable for storing I/O statusinformation.

Also shown in FIG. 22 are a plurality of locations that storeintermediate status information, labeled IM-11, IM-21, IM-22, and IM-41.The intermediate states IM-11, IM-21, IM-22, and IM-41 are processedversions of selected I/O states. For example, input signals may beprocessed for purposes of scaling, unit conversion and/or calibration,and it may be useful in some cases to store the processed I/O statusinformation. Alternatively, the intermediate states IM-11, IM-21, IM-22,and IM-41 may be a function of a plurality of I/O states that incombination have some particular significance. The processed I/O statusinformation is then transmitted to the remaining interface modules 1420.

Referring now to FIGS. 23-24, FIG. 23 is a flowchart describing theoperation of the control system of FIG. 21, and FIG. 24 is a data flowdiagram describing data flow through an exemplary interface moduleduring the process of FIG. 23. As an initial matter, it should be notedthat although FIG. 23 depicts a series of steps which are performedsequentially, the steps shown in FIG. 23 need not be performed in anyparticular order. In practice, for example, modular programmingtechniques are used and therefore some of the steps are performedessentially simultaneously. Additionally, it may be noted that the stepsshown in FIG. 23 are performed repetitively during the operation of theinterface module 1421, and some of the steps are in practice performedmore frequently than others. For example, input information is acquiredfrom the input devices more often than the input information isbroadcast over the communication network. Although the process of FIG.23 and the data flow diagram of FIG. 24 are primarily described inconnection with the interface module 1421, the remaining interfacemodules 1422-1425 operate in the same manner.

At step 1852, the interface module 1421 acquires input statusinformation from the local input devices 1541. The input statusinformation, which pertains to the input states I-11 to I-15 of theinput devices 1541, is transmitted from the input devices 1541 to theinterface module 1421 by way of respective dedicated communicationlinks, as previously described in connection with FIGS. 3-4. At step1854, the input status information acquired from the local input devices1541 is stored in the I/O status table 1520 at a location 1531. For theinterface module 1421, the I/O devices 1541 and 1551 are referred to aslocal I/O devices since the I/O devices 1541 and 1551 are directlycoupled to the interface module 1421 by way of respective dedicatedcommunication links, as opposed to the remaining non-local I/O devicesand 1542-1545 and 1552-1555 which are indirectly coupled to theinterface module 1421 by way of the communication network 1661.

At step 1856, the interface module 1421 acquires I/O status informationfor the non-local input devices 1542-1545 and the non-local outputdevices 1552-1555 by way of the communication network 1661.Specifically, the interface module 1421 acquires input statusinformation pertaining to the input states I-21 to I-25, I-31 to I-35,I-41 to I-45, I-51 to I-55 of the input devices 1542-1545, respectively,and acquires output status information pertaining to the output statesO-21 to O-25, O-31 to O-35, O-41 to O-45, O-51 to O-55 of the outputdevices 1552-1555. The input status information and the output statusinformation are stored in locations 1533 and 1534 of the I/O statustable 1520, respectively.

At step 1860, the interface module 1421 determines desired output statesO-11 to O-15 for the output devices 1551. As previously noted, each ofthe interface modules 1420 stores a chassis control program 1840, one ormore variant control programs 1842, and an auxiliary control program1844. The interface module 1421 is associated with the chassis controlsystem 1511 and, therefore, executes a portion of the chassis controlprogram 1840. (The portion of the chassis control program 1840 executedby the interface module 1421 is determined by the location of theinterface module 1421 on the military vehicle 1410, as previouslydescribed.) The interface module 1421 executes the chassis controlprogram 1840 to determine the desired output states O-11 to O-15 basedon the I/O status information stored in the I/O status table 1520.Preferably, each interface module 1420 has complete control of its localoutput devices 1450, such that only I/O status information istransmitted on the communication network 1460 between the interfacemodules 1420.

At step 1862, the interface module 1421 controls the output devices 1551in accordance with the desired respective output states O-11 to O-15.Once the desired output state for a particular output device 1551 hasbeen determined, control is achieved by transmitting a control signal tothe particular output device 1551 by way of a dedicated communicationlink. For example, if the output is a digital output device (e.g., aheadlight controlled in on/off fashion), then the control signal isprovided by providing power to the headlight by way of the dedicatedcommunication link. Ordinarily, the actual output state and the desiredoutput state for a particular output device are the same, especially inthe case of digital output devices. However, this is not always thecase. For example, if the headlight mentioned above is burned out, theactual output state of the headlight may be “off,” even though thedesired output state of the light is “on.” Alternatively, for an analogoutput device, the desired and actual output states may be different ifthe control signal is not properly calibrated for the output device.

At step 1864, the interface module 1421 stores output status informationpertaining to the desired output states O-11 to O-15 for the outputdevices 1551 in the I/O status table 1520. This allows the output statesO-11 to O-15 to be stored prior to being broadcast on the communicationnetwork 1661. At step 1866, the interface module 1421 broadcasts theinput status information pertaining to the input states I-11 to I-15 ofthe input devices 1541 and the output status information pertaining tothe output states O-11 to O-15 of the output devices 1551 over thecommunication network 1661. The I/O status information is received bythe interface modules 1422-1425. Step 1866 is essentially the oppositeof step 1856, in which non-local I/O status information is acquired bythe interface module 1421 by way of the communication network 1661. Inother words, each interface module 1420 broadcasts its portion of theI/O status table 1520 on the communication network 1661, and monitorsthe communication network 1661 for broadcasts from the remaininginterface modules 1420 to update the I/O status table 1520 to reflectupdated I/O states for the non-local I/O devices 1441 and 1451. In thisway, each interface module 1420 is able to maintain a complete copy ofthe I/O status information for all of the I/O devices 1441 and 1451 inthe system.

The interface modules 1423 and 1425 are used to transmit I/O statusinformation between the various control systems 151I-1513. Specifically,as previously noted, the interface module 1423 is connected to both thecommunication network 1661 for the chassis control system 1511 and tothe communication network 1662 for the variant control system 1512 (seeFIG. 17). The interface module 1423 is preferably utilized to relaybroadcasts of I/O status information back and forth between theinterface modules 1421-1425 of the chassis control system 1511 and theinterface modules 1426-1428 of the variant control system 1512.Similarly, the interface module 1425 is connected to both thecommunication network 1661 for the chassis control system 1511 and theto the communication network 1663 for the auxiliary control system 1513(see FIG. 17), and the interface module 1425 is preferably utilized torelay broadcasts of I/O status information back and forth between theinterface modules 1421-1425 of the chassis control system 1511 and theinterface modules 1429-1430 of the auxiliary control system 1513.

The arrangement of FIGS. 21-24 is advantageous because it provides afast and efficient mechanism for updating the I/O status information1848 stored in the data memory 1834 of each of the interface modules1420. Each interface module 1420 automatically receives, at regularintervals, complete I/O status updates from each of the remaininginterface modules 1420. There is no need to transmit data request(polling) messages and data response messages (both of which requirecommunication overhead) to communicate information pertaining toindividual I/O states between individual I/O modules 1420. Although moreI/O status data is transmitted, the transmissions require less overheadand therefore the overall communication bandwidth required is reduced.

This arrangement also increases system responsiveness. First, systemresponsiveness is improved because each interface module 1420 receivescurrent I/O status information automatically, before the information isactually needed. When it is determined that a particular piece of I/Ostatus information is needed, there is no need to request thatinformation from another interface module 1420 and subsequently wait forthe information to arrive via the communication network 1661. The mostcurrent I/O status information is already assumed to be stored in thelocal I/O status table 1520. Additionally, because the most recent I/Ostatus information is always available, there is no need to make apreliminary determination whether a particular piece of I/O statusinformation should be acquired. Boolean control laws or other controllaws are applied in a small number of steps based on the I/O statusinformation already stored in the I/O status table 1520. Conditionalcontrol loops designed to avoid unnecessarily acquiring I/O statusinformation are avoided and, therefore, processing time is reduced.

It may also be noted that, according to this arrangement, there is noneed to synchronize the broadcasts of the interface modules 1420. Eachinterface module 1420 monitors the communication network 1661 todetermine if the communication network 1661 is available and, if so,then the interface module broadcasts the I/O status information forlocal I/O devices 1441 and 1451. (Standard automotive communicationprotocols such as SAE J1708 or J1939 provide the ability for each memberof the network to monitor the network and broadcast when the network isavailable.) Although it is desirable that the interface modulesrebroadcast I/O status information at predetermined minimum intervals,the broadcasts may occur asynchronously.

The technique described in connection with FIGS. 21-24 also provides aneffective mechanism for detecting that an interface module 1420 has beenrendered inoperable, for example, due to damage incurred in combat. Asjust noted, the interface modules 1420 rebroadcast I/O statusinformation at predetermined minimum intervals. Each interface module1420 also monitors the amount of time elapsed since an update wasreceived from each remaining interface module 1420. Therefore, when aparticular interface module 1420 is rendered inoperable due to combatdamage, the inoperability of the interface module 1420 can be detectedby detecting the failure of the interface module 1420 to rebroadcast itsI/O status information within a predetermined amount of time.Preferably, the elapsed time required for a particular interface module1420 to be considered inoperable is several times the expected minimumrebroadcast time, so that each interface module 1420 is allowed acertain number of missed broadcasts before the interface module 1420 isconsidered inoperable. A particular interface module 1420 may beoperable and may broadcast I/O status information, but the broadcast maynot be received by the remaining interface modules 1420 due, forexample, to noise on the communication network.

This arrangement also simplifies the operation of the data logger 1485and automatically permits the data logger 1485 to store I/O statusinformation for the entire control system 1412. The data logger 1485monitors the communication network 1661 for I/O status broadcasts in thesame way as the interface modules 1420. Therefore, the data logger 1485automatically receives complete system updates and is able to storethese updates for later use.

As previously noted, in the preferred embodiment, the interface modules1423 and 1425 are used to transmit I/O status information between thevarious control systems 1511-1513. In an alternative arrangement, theinterface module 1429 which is connected to all three of thecommunication networks 1661-1663 could be utilized instead. Althoughless preferred, the interface module 1429 may be utilized to receive I/Ostatus information from each of the interface modules 1421-1428 and1430, assemble the I/O status data into an updated I/O status table, andthen rebroadcast the entire updated I/O status table 1520 to each of theremaining interface modules 1421-1428 and 1430 at periodic or aperiodicintervals. Therefore, in this embodiment, I/O status information for theall of the interface modules 1420 is routed through the interface module1429 and the interface modules 1420 acquire I/O status information fornon-local I/O devices 1440 and 1450 by way of the interface module 1429rather than directly from the remaining interface modules 1420.

From the foregoing description, a number of advantages of the preferredmilitary vehicle control system are apparent, some of which have alreadybeen mentioned. First, the control system is constructed and arrangedsuch that failure at a single location does not render the entirevehicle inoperable. The control system has the ability to dynamicallyreconfigure itself in the event that one or more interface modules arelost. By avoiding the use of a central control unit that is fixed at onelocation, and using a moving central control unit, there is no singlepoint failure. If a master interface modules fails, another interfacemodule will assume the position of the central control unit.

Additionally, because the interface modules are interchangeable, if oneinterface module is damaged, it is possible to field service the controlsystem by swapping interface modules, obtained either from within thevehicle itself or from another vehicle, even if the other vehicle is notthe same variant type. This allows the effectiveness of the militaryvehicle to be maximized by allowing undamaged interface modules to beutilized in the most optimal manner.

The use of the control system 1412 in connection with multipurposemodular vehicles is also advantageous. When the variant module ismounted to the chassis, all that is required is to connect power, groundand the communication network. Only one connector is required for all ofthe different types of variants. This avoids the need for a separateconnector on the chassis for each different type of variant module,along with the additional unutilized hardware and wiring, as hasconventionally been the approach utilized.

Moreover, since every interface module has a copy of the applicationprogram, it is possible to test each interface module as an individualunit. The ability to do subassembly testing facilitates assembly of thevehicle because defective mechanisms can be replaced before the entirevehicle is assembled.

Finally, the advantages regarding flexibility, robustness, ease of use,maintainability, and so on, that were discussed above in connection withfire fighting vehicles also apply to military vehicles. For example, itis often desirable in military applications to provide vehicles withconsoles for both a left-hand driver and a right-hand driver. Thisoption can be implemented without complex wiring arrangements with thepreferred control system, due to the distributed data collection and theintelligent processing of information from input devices. Likewise,features such as “smart start” (in which vehicle starting is controlledautomatically to reduce faulty starts due to operator error) can beimplemented by the control system without any additional hardware.

C. Electric Traction Vehicle

Referring now to FIGS. 25-29, a control system for an electric tractionvehicle 1910 is shown. An electric traction vehicle is a vehicle thatuses electricity in some form or another to provide all or part of thepropulsion power of the vehicle. This electricity can come from avariety of sources, such as stored energy devices relying on chemicalconversions (batteries), stored electrical charge devices (capacitors),stored energy devices relying on mechanical stored energy (e.g.flywheels, pressure accumulators), and energy conversion products. Ahybrid electric vehicle is an electric traction vehicle that uses morethan one sources of energy, such as one of the electrical energy storagedevices mentioned above and another source, such as an internalcombustion engine. By having more than one source of energy someoptimizations in the design can allow for more efficient powerproduction, thus one can use power from different sources to come upwith a more efficient system for traction. The disclosure herein can beused to implement electric vehicles in general and/or hybrid electricvehicles in particular. The electric vehicle 1910 can implement any ofthe other vehicle types described herein (e.g., fire fighting vehicle,military vehicle, snow blower vehicle, refuse-handling vehicle, concretemixing vehicle) as well as others not described herein. Thus, thefollowing teachings regarding the electric vehicle system may becombined with any/all of the teachings contained herein.

The electric traction vehicle 1910 preferably comprises a vehicleplatform or vehicle support structure 1912, drive wheels 1914, a powersource or principal power unit 1916, a power storage unit 1922, electricmotors 1928, servo or drive controllers 1930, an energy dissipationdevice 1932, and interface modules 1934. The vehicle 1910 furthercomprises a control system with a plurality of input and output deviceswhich vary depending on the application for which the vehicle 1920 isused. For example, if the vehicle 1910 is a fire truck, then the vehicle1910 has input and output devices such as those described in connectionwith FIGS. 1-13 in connection with the fire truck 10. Except to theextent that different I/O devices are used, the control system the sameas the control system 1412 as described in FIGS. 14-24 and is used toreceive inputs from these input devices and control these outputdevices. The interface modules 1934 are part of this control system andpreferably are constructed and operate in the same manner as theinterface modules 1420 as described above. Specifically, each interfacemodule 1934 may process its own inputs and outputs based on I/O statusinformation received via I/O status broadcasts from the other interfacemodules 1934.

Interconnecting the interface modules 1934 on the electric tractionvehicle 1910 is a communication network 1976 and an AC power busassembly 1942 through which the vehicle and its various functions arecontrolled and operated. The communication network 1976 corresponds tothe communication network 60 of FIG. 2 in the case of an electric firetruck vehicle and to the communication network 1460 in the case of aelectric military vehicle. The communication network 1976 is used tocommunication I/O status information between the interface modules 1934.The AC bus assembly 1942 is a power transmission link and corresponds tothe power transmission link 102 of FIG. 2 in the case of an electricfire truck vehicle and to the power transmission link 1502 of FIG. 15 inthe case of an electric military vehicle. Also connected to the AC busassembly 1942 are the principal power unit 1916, the power storage unit1922, and the energy dissipation device 1932. The interface modules 1934include rectifier circuitry to convert AC power from the AC bus assembly1942 to DC power for output devices such as LED indicators. Also, it maybe noted that the AC power is also provided directly to the drivecontrollers 1930, which operate under the control of the interfacemodules 1934. It is also contemplated that wireless communicationbetween the interface modules 1934 and the various modules 1984 can beachieved including communication of signals 1974 via radio waves,microwaves, and fiber optical paths including relay via satellite to acentral command center.

With reference to FIG. 32A-32B, it may be noted that manycommercially-available servo drive controllers may be network-enabledand therefore an option exists as to the manner in which the interfacemodules 1934 are connected to the drive controllers 1930. Thus, in FIG.32A, each interface module 1934 is connected to one or more drivecontrollers 1930 by way of dedicated communication links for hardwiredcontrol of the drive controllers 1930. In the illustrated embodiment,three digital links and one analog link are shown for each drivecontroller 1930 representing, for example, a stop/run output, aforward/reverse output, a generation/regeneration output, and a variabletorque command (0-100%) output from the interface module 1934. Asindicated in FIG. 25, power from the AC bus assembly 1942 is preferablyprovided directly to the drive controllers 1930 (rather than through theinterface modules 1934), and therefore each of the dedicatedcommunication links is used to transmit only information and not power.Each interface module 1934 is then connected to the communicationnetwork 1976 which, in FIG. 32A, is implemented as two separate networks(e.g., a network dedicated for use with the interface modules 1934, anda separate J1939 network to connect to the electronic control units forthe engine, transmission, anti-lock brake and central tire inflationsystems).

In FIG. 32B, each interface module 1934 is connected to one or moredrive controllers 1930 by way of a communication network for networkcontrol of the drive controllers 1930. The same information may betransmitted as in FIG. 32A except that the information is transmitted byway of the communication network. Because the AC bus assembly 1942 isconnected directly to the drive controllers 1930, there is no need totransmit power from the interface modules 1934 to the drive controllers1930. Each interface module 1934 is then connected to the communicationnetwork 1976. If only two network ports are included on the interfacemodules 1934, then information obtained from the electronic controlunits for the engine, transmission, anti-lock brake and central tireinflation systems may be obtained from other interface modules (notshown) connected to a J1939 network. Alternatively, the interfacemodules 1934 may be provided with a third network port.

The electric motors 1928 are appropriately sized traction motors. Anexemplary embodiment of an electric traction vehicle 1910 employs an AC,three phase induction electric motor having a simple cast rotor, machinemount stator and sealed ball bearings. An induction motor is preferredbecause it avoids brushes, internal switches and sliding contactdevices, with the rotor being the only moving part of the tractionmotor. Control of the electric motor 1928 is achieved by the interfacemodule 1934 through the drive controller 1930 which is coupled to themotor 1928. The torque output of the motor 1928 is adjusted based oninputs received from the operator and transmitted to the interfacemodule 1934 over the communication network 1976.

The drive wheels 1914 are rotatably mounted on the vehicle platform 1912with an electric motor 1928 coupled to at least one wheel 1914. In oneembodiment, the drive wheels 1914 are each be coupled to respectiveelectric motors 1928, which in turn are each coupled to respective drivecontrollers 1930, which in turn are coupled to respective interfacemodules 1934.

Various embodiments of an electric traction vehicle 1910 are based onthe number of wheels 1914 that are driven on the vehicle 1910. Forinstance, one embodiment includes a drive wheel 1914 coupled to anelectric motor 1928, which in turn is coupled to a drive controller1930, which in turn is coupled to an interface module 1934, which inturn is coupled to other interface modules (for other vehicle I/O) byway of the communication network 1976. The vehicle can also include fourdrive wheels 1914 coupled to four respective electric motors 1928, whichin turn are coupled to four respective drive controllers 1930, which inturn are coupled to four respective interface modules 1934, which inturn are coupled to other interface modules and to each other by way ofthe communication network 1976. In the embodiment of FIG. 1, eight drivewheels 1914 are coupled to eight respective electric motors 1928, whichin turn are coupled to eight respective drive controllers 1930, which inturn are coupled to eight respective interface modules 1934, which inturn are coupled to other interface modules and to each other by way ofthe communication network 1976. Other configurations may also be used,and the ratio of motors, wheels, servo drives and interface modules neednot be one-to-one relative to each other. Thus, for example, eachinterface module 1934 may control one wheel, one axle, a tandem set ofaxles, or other set of wheels. As described in greater detail below, thevehicle 1910 can also include pairs of drive wheels 1914 which aredriven in tandem by a respective one of the plurality of electric motors1928. Typically, at least two of the wheels are steerable.

The torque output of each motor 1928 is adjusted to meet therequirements established in the associated interface module 1934 fromthe I/O status information. The electric motors 1928 may operate toproduce electric torque to drive the drive wheels 1914 or may operate ina regenerative braking mode to provide power to the power storage unit1922, as determined by inputs received from an operator of the electrictraction vehicle 1910.

The electric traction vehicle 1910 can be configured with one or moremodular independent coil spring suspensions for steerable andnon-steerable wheel assemblies and driver and non-driver axles. Detailsof such modular independent coil spring suspensions can be found in U.S.Pat. Nos. 5,538,274, 5,820,150, and 6,105,984 incorporated herein bythis reference, which are assigned to the assignee of the presentinvention.

The principal power unit 1916 and the power storage unit 1922 aremounted on the vehicle platform 1912. As previously noted, the principalpower unit 1916 provides power for multiple electric motors 1928 coupledto individual drive wheels 1914. This simplifies the transmission ofpower to the wheels 1914 as compared to a non-electric vehicle byeliminating the torque converter, transmission, transfer case, and driveshafts. Further, because multiple electric motors 1928 are used, thehorse power requirements of each electric motor 1928 are such thatstandard commercially available electric motors may be used even in thecase of a heavy duty military vehicle.

The principal power unit 1916 includes a prime mover or engine 1918coupled to a generator or alternator 1920. The prime mover 1918 can be agas turbine or an internal combustion engine. The principal power unit1916 can also be a fuel cell or a nuclear power device. The fuel cellmay for example be a hydrogen-oxygen fuel cell that produces electricalpower in the process of a chemical reaction that combines oxygen andhydrogen to create water. If a DC source is used, an inverter may beused to convert DC power from the DC source to AC power for the AC busassembly 1942. In the preferred embodiment, the prime mover 1918 is adiesel engine optimized for operation at a constant speed (revolutionsper minute). Operating the diesel engine at a constant, optimal speedeliminates inefficiencies associated with changing RPM levels duringacceleration and deceleration, improves overall efficiency, and reducesemissions.

The generator/alternator 1920 is preferably a synchronous generatorproducing 460 to 480 volts, three phase, AC 60 Hz power for the electrictraction vehicle 1910. However, it is contemplated that different sizedgenerators or alternators can be coupled to the prime mover for purposesof generating either higher or lower electrical power. For instance, asingle phase system can be utilized or a system that generates 720 voltpower system can be used or a system that operates at a frequency otherthan 60 Hz, such as 50 Hz which is typical in European countries. It isalso contemplated that the power generated by the principal power unit1916 can be modified by appropriate auxiliary modules such as astep-down transformer to provide power to operate ancillary equipment onor associated with the electric traction vehicle 1910 such as pumps,instruments, tools, lights, and other equipment.

The AC bus assembly 1942 includes a plurality of phase conductors 1944.A first conductor 1946 having a first end 1948 and second end 1950together with a second conductor 1952 having a first end 1954 and asecond end 1956 can be configured together with a neutral 1964 toprovide single phase power in one embodiment of the vehicle 1910. Athird conductor 1958 having a first end 1960 and a second end 1962 canbe used in conjunction with the first conductor 1946 and the secondconductor 1952 to provide three phase power as shown in FIG. 1. Theconductors 1944 can be stranded metal wire such as copper or aluminumsized and clad to transmit the power generation contemplated in thevehicle 1910 design. The conductors 1944 can also be solid metal bars,generally referred to as bus bars, composed of appropriate clad metals,such as copper or aluminum, as will be appreciated by one ordinarilyskilled in the art.

Also connected to the AC power bus assembly 1942 is the power storageunit 1922, as previously mentioned. The power storage unit 1922 includesan electric power converter 1924 and an energy storage device 1926. Thepower storage unit 1922 can be configured to provide electric powerabove and beyond that required of the principal power unit 1916. Theenergy storage device 1926 can be electric capacitors, storagebatteries, a flywheel, or hydraulic accumulators. The electric powerconverter 1924 can be configured to convert the AC power generated bythe principal power unit 1916 to DC power and transfer such convertedpower to the storage device 1926. The electrical power converter 1924can also convert the energy stored in the energy storage device 1926back to AC power to augment and supplement the AC power generated by theprincipal power unit 1916 over the AC power bus assembly 1942.Applicants have determined that additional horsepower of short-termpower can be provided into the AC power bus assembly 1942 over the phaseconductors 1944 by discharge of an on-board capacitor or battery pack(energy storage device 1926) under control of the power storage unit1922. (Depending on the application, the additional power may be in therange of 100-600 or more horsepower, such as 200-300 horsepower.) In oneembodiment, the energy storage device 1926 is formed of a bank ofultracapacitors, such as the PC 2500 ultracapacitor available fromMaxwell Technologies, 9244 Balboa Avenue San Diego, Calif. 92123. Thesedevices provide a high electrical energy storage and power capacity andhave the ability to deliver bursts of high power and recharge rapidlyfrom an electrical energy source/sink over hundreds of thousands ofcycles.

An advantage constructing the energy storage device 1926 of capacitorsis that capacitors are relatively easy to discharge. Therefore, it ispossible to discharge the energy storage device 1926 when maintenance isto be performed on the vehicle 1910 to avoid electrocution ofmaintenance personnel. In FIG. 25, the power storage unit 1922(including the energy storage device 1926) operates under the control ofone of the interface modules 1934. In one embodiment, the interfacemodule 1934 is used to discharge the energy storage device responsive tooperator inputs. For example, a capacitor discharge switch may beprovided in the cab of the vehicle 1910 and/or near the energy storagedevice 1926 and coupled to a nearby interface module 1934. When theoperator activates the switch, the interface modules 1934 cooperateresponsive to ensure that no electrical power is being coupled to the ACbus assembly 1942 by the generator 1920 and any other power generatingdevices, such that the energy storage device 1926 is the only powersource coupled to the AC bus assembly 1942 (e.g., when the prime moveror engine 1918 is not moving or is not coupled to the AC bus assembly1942, the generator 1920 does not provide electrical power to the AC busassembly 1942). Therefore, any stored electrical power in the energystorage device 1926 dissipates to power consuming devices that arecoupled to the AC bus assembly 1942. A variety of power consumingdevices may be provided for this purpose. For example, an energydissipation device 1932 (described in greater detail below) may be usedfor this purpose. The dissipating capacity (e.g., resistor size andpower ratings) of the energy dissipation device may be determined as afunction of the desired amount of discharge time. Other power consumingdevices already coupled to the AC bus assembly 1942, such as an enginecooling fan, may also be used. In this configuration, the interfacemodule 1934 to which the engine cooling fan is connected turns on theengine cooling fan when it is determined that the operator input at thecapacitor discharge switch has been received.

The power storage unit 1922 may be coupled to the communication network1976 and controlled by the interface module 1934. The combinedelectrical power from the principal power unit 1916 and the powerstorage unit 1922 will all be available on the AC power bus assembly1942 for use by the electric motors 1928 or by any other module 1984 orauxiliary module 1986 as determined by the operator at the userinterface 1936 of the interface module 1934.

In operation, the power storage unit 1922 receives power from theprincipal power unit 1916 over conductors 1944 of the AC power busassembly 1942. The power received is converted into the appropriateenergy mode required by the energy storage device 1926 and maintained inthe energy storage device 1926 until required during the operation ofthe vehicle 1910. If the principal power unit 1916 is not functioningfor any reason, the energy in the power storage unit can be utilized tooperate, for a given period of time, the vehicle 1910 or any of themodules 1984 or auxiliary modules 1986 mounted on the vehicle 1910. Inthe context of a military vehicle, the power storage unit 1922 may alsobe used in stealth modes of operation to avoid the noise associated withthe prime mover (e.g., diesel engine) 1918 and the generator 1920.

Energy storage recharge of the power storage unit 1922 by the principalpower unit 1916 begins automatically and immediately after the vehicle1910 arrives at its destination and continues during the vehicle'sreturn run to its original location. The state of charge of the powerstorage unit 1922 is maintained between missions by a simple plugconnection to a power receptacle in the vehicle's garage or storagelocation, which receptacle will automatically disconnect as the vehicle1910 leaves such site. The power storage unit 1922 can also receiveenergy generated by the electric motors 1928 when the motors areconfigured in a regeneration mode in which case they function as agenerator. Such functionality is utilized in a braking procedure for thevehicle as determined by the operator at a user interface 1936 (see FIG.26). The electric motor 1928 and AC power bus assembly 1942 can also beconfigured to regenerate power back to the principal power unit 1916.

As shown in FIG. 26, the vehicle 1910 can also serve as an on-site powersource for off-board electric power consuming devices 1951. For example,in the context of a military vehicle, the vehicle 1910 can serve as amobile electric generator. When the vehicle is stationary, the electricmotors 1928 consume substantially zero power. Therefore, electric powerthat would otherwise be used to drive movement of the vehicle 1910 canbe supplied to off-board equipment. In the context of an ARFF vehicle,if an airport loses electricity due to a failure in the power grid, anARFF vehicle that implements the system described herein can be used togenerate power for the airport by connecting the power bus for theairport to the AC bus assembly 1942 through the use of a suitableconnector. Likewise, at the scene of a fire, the AC bus assembly 1942can be used to provide power for scene lighting. In one preferredembodiment, the power generating capacity of the vehicle 1910 is in theneighborhood of about 500 kilowatts of electricity, which is enough topower approximately 250-300 typical homes. Depending on the size of thevehicle 1910 and the principal power unit 1916, the power generatingcapacity may be smaller (e.g., 250 kilowatts) or larger (e.g., 750kilowatts). Additionally, because the AC bus assembly 1942 provides480V, three phase, AC 60 Hz power, which is commonly used in industrialsettings, there is no need to convert the power from the AC bus assembly1942. In this regard, in FIG. 26, the off-board power-consuming devices1951 are shown not to be connected to the communication network 1976,because the power provided by the AC bus assembly 1942 can be providedto a variety of standard devices, including devices which are notspecifically designed for use with the vehicle 1910.

Preferably, an energy dissipation device 1932 is coupled to the AC busassembly 1942 and the communication network 1976. If it is determinedthat the principal power unit 1916 or the electric motors 1928 or anyother auxiliary module 1986 generating too much power or are notutilizing sufficient power, the excess power can be dissipated throughthe energy dissipation device 1932. An example of an energy dissipationdevice 1932 is a resistive coil that may be additionally cooled by fansor an appropriate fluid. Another example of an energy dissipation device1932 is a steam generator which utilizes excess heat generated in thevehicle to heat water to produce steam. Another example of an energydissipation device is to have the system back feed the generator to actas a motor and use the engine as an air pump to pull power out of thesystem. The energy dissipation device, for example, may be used duringregenerative braking when the level of charge in the capacitor bankforming the energy storage device 1926 is near its peak.

Referring now to FIG. 27, selected aspects of the vehicle 1910 of FIG.25 are shown in greater detail. The vehicle 1910 further comprises anoperator interface 1973 which includes a throttle pedal 1975, brakepedal 1977, shift control 1979, and steering wheel 1981. In FIG. 27,these input devices are shown as being connected to a common interfacemodule 1934 which is connected to the communication network 1976 alongwith the interface modules 1934 coupled to the electric motors 1928(only one of which is shown in FIG. 26). Although the input devices1975-1981 are shown as being coupled to a common same interface module,the input devices may also be coupled to different interface modules.The operator interface may also receive inputs from other input devicesto raise or lower the vehicle, lock the suspension, control aload-handling system, and control vehicle operation in stealth modes ofoperation (e.g., operating exclusively on the power storage unit 1922).The operator interface 1973 may include a display that displaysinformation to the operator such as speed, charge level of the storageunit 1922, generator efficiency, direction of travel, alarm status, fueleconomy, temperatures, pressures, and data logging information.

Each interface module 1934 receives the I/O status information from theoperator interface 1973. For those interface modules that are connectedto a respective drive controller 1930 and electric motor 1928, the I/Ostatus information from the operator interface 1973 is processed toprovide control signals to control the electric motor 1928. This processis shown in FIG. 27.

Referring now to FIG. 28, at step 2010, throttle, brake, shift, andsteering inputs are received from the operator at the interface module1934 which is connected to the operator interface 1973. At step 2012,the throttle, brake, shift and steering inputs are transmitted by way ofthe communication network 1976 (during I/O status broadcasts aspreviously described). At step 2014, this information is received ateach of the remaining interface modules 1934. At step 2016, theinterface modules 1934 that control the electric motors 1928 use thethrottle, brake, shift and steering inputs to control the electricmotors 1928. To this end, the interface modules 1934 determine a speedor torque command and provide this command to the drive controller 1930.Other information, such as vehicle weight, minimum desired wheel speed,wheel slip control parameters, and other information may also be used.Although the vehicle 1910 does not include a mechanical transmission,the shift input from the shift input device 1979 may be used to causethe electric motors 1928 to operate at different operating pointsdepending on a status of the shift input device, with each of theoperating points corresponding to different torque productioncapabilities (or different tradeoffs between vehicleresponsiveness/acceleration capability and motor efficiency).

Each interface module 1934 preferably includes a number of controlsubprograms, including a subprogram 1983 for differential speed control,a subprogram 1985 for regenerative brake control, a subprogram 1987 forefficiency optimization control, and a configuration interface 1989.These programs provide for further control of the torque/speed commandgiven by each interface module 1934 to the respective drive controller1930.

The differential speed control program 1987 accepts the steering angleas an input and controls the motor speed of each motor 1928 such thatthe wheels 1914 rotate at slightly different speeds during vehicleturning maneuvers. The differential speed control program 1987 is anelectronic implementation of a mechanical differential assembly. Thesteering angle input may also be used by another interface module 1934to control a steering mechanism of the vehicle 1910 to thereby control adirection of travel of the vehicle 1910. Preferably, steering controltakes into account other I/O status information (such as vehicle speed)and is optimized to avoid vehicle slippage (“scrubbing”) during turnmaneuvers. The differential speed control program 1987 monitors motortorque output along with other system parameters such that the speeddifference between motors does not go above a predefined limit. This canbe controlled both side by side and front to back and combinations ofboth. By commanding torque and monitoring and adjusting for speeddifference, optimal tractive force can be put to ground in any tractioncondition.

Regenerative brake control program 85 controls the motor 1928 such thatthe motor provides a braking action to brake the vehicle 1910 inresponse a regeneration/auxiliary signal is received. For example, asignal may be received from a brake pedal request (the brake pedal 1977is pressed), no TPS count, or other user controlled input/switch. Thiscauses the motor 1928 to act as a generator to regenerate power back tothe power storage unit 1922 or the principal power unit 1916 via the ACbus assembly 1942. In addition to regenerative braking, a standardanti-lock brake system is also used.

The efficiency optimization control program 87 controls motor speed andtorque conditions to allow a first subset of the motors 1928 to operateat an optimal power for a particular speed, and a second subset of themotors 1928 to operate in a regenerative mode. Having one set of motorsoperate 1928 at an optimal power for a particular speed and a second setof motors 1928 operate in a regenerative mode is more efficient anddraws less net power than having all of the motors 1928 operating at anon-optimal speed. Alternative power matching schemes may also be usedin which optimum efficiency for some of the motors 1928 is reached byhaving some of the remaining motors 1928 operate in a non-torqueproducing mode.

Configuration interface program 1989 allows for reconfiguration of thevehicle 1910 depending on which types of auxiliary modules are mountedto the vehicle 1910. The configuration program 1989 detects what type ofauxiliary modules are connected to the vehicle, and adjusts theconfiguration of the control program executed by the interface modules1934 to take into account the particular configuration of the vehicle1910 as determined by which auxiliary modules are present.

In particular, in the preferred embodiment, the principal power unit1916, the power storage unit 1922, and the energy dissipation device1932 are provided as auxiliary modules 1984 that are removably mountedon the vehicle platform and are removably connected to the communicationnetwork 1976 and the AC bus assembly 1942 by way of a suitable connectorassembly. Other auxiliary modules 1986 may also be provided. Anauxiliary module 1986 can be any type of equipment or tool required orassociated with the function and operation of the vehicle 1910. Forexample, the auxiliary module can be a pump, a saw, a drill, a light,etc. The auxiliary module 1986 is removably connected to thecommunication network 1976 and the AC bus assembly 1942. A junction 1988is used to facilitate the connection of the modules to the communicationnetwork 1976 and the AC power bus assembly 1942 and multiple junctions1988 are located at convenient locations throughout the vehicle 1910.The junctions 1988 can accommodate various types of connections such asquick connectors, nuts and bolts, solder terminals, or clip terminals orthe like. The junction 1988 can include a connector to accommodateconnection to the communication network 1976 and/or the AC bus assembly1942. Additional auxiliary modules can be added to the vehicle 1910 ascircumstances and situations warrant.

In the preferred embodiment, and as shown in FIG. 29, auxiliary drivemodules 1953 are used that each include a respective one of the drivewheels 1914, a respective one of the electric motors 1928, a respectiveone of the drive controllers 1930, and a respective one of the interfacemodules 1934. Like the other auxiliary modules discussed above, theauxiliary drive modules 1953 are capable of being removed, replaced, andadded to the vehicle 1910. To this end, each auxiliary drive moduleincludes an electrical connector that mates with a compatible electricalconnector one the vehicle platform 1912 and a mechanical mounting system(e.g., a series of bolts) that allows the auxiliary drive module 1953 tobe quickly mounted to or removed from the vehicle 1910. The electricalconnector connects the interface module 1934 to a communication network1976 and connects the drive controller 1930 to the AC bus assembly 1942.Therefore, if one auxiliary drive module 1953 malfunctions, theauxiliary drive module 1953 can be removed and replaced with a properlyfunctioning auxiliary drive module 1953. This allows the vehicle 1910 toreturn immediately to service while the inoperable drive module isserviced. This arrangement also allows the same vehicle to be providedwith different drive capacities depending on intended usage. Forexample, under one usage profile, the vehicle 1910 may be provided withfour auxiliary drive modules 1953. Under a second usage profile, thevehicle 1910 may be provided with two additional auxiliary drive modules1953′ for extra drive capacity. Additionally, the vehicle platform 1912is preferably a generic vehicle platform that is used with severaldifferent types of vehicles having different application profilesrequiring different drive capacities. In this regard, it may also benoted that the principal power unit 1916 is also capable of beingremoved and replaced with a principal power unit 1916 with a largerelectric generation capacity. This feature is therefore advantageous inthat auxiliary drive modules 1953 are capable of being added to andremoved from the vehicle as a unit to achieve a corresponding increaseor decrease in the drive capacity of the vehicle 1910, thereby givingthe vehicle 1910 a reconfigurable drive capacity. As previouslyindicated, the system can be configured to have one of the interfacemodules 1934 control a single drive wheel 1914, an entire axle assembly(one or two motor configuration) as well as a tandem axle assembly (oneand two motor axle configurations), as well as other permutations andcombinations.

Referring to FIG. 28, FIG. 28 shows the operation of the configurationprogram 1989. At step 2020, it is detected that there has been a changein vehicle configuration. The auxiliary module may be any of theauxiliary modules described above. Step 2020 comprises detecting that anauxiliary module has been added in the case of an added auxiliarymodule, and comprises detecting that an auxiliary module has beenremoved in the case of a removed auxiliary module. If an auxiliarymodule has been rendered in operable (e.g., one of the electric motors1928 has failed), then step 2020 comprises detecting that the inoperableauxiliary module has failed.

At step 2022, the configuration change is characterized. For example, ifan auxiliary module has been added or removed, the type and location ofthe added/removed auxiliary module is determined. If one auxiliarymodule has been replaced with another auxiliary module, the location atwhich the change was made as well as the module type of the added andremoved auxiliary modules is determined. In the case where the auxiliarymodule comprises an interface module 1934, the different characteristicsof the different auxiliary modules may be stored in the respectiveinterface modules 1934. As a result, step 2022 may be performed byquerying the interface module 1934 of the removed auxiliary module(before it is removed) and by querying the interface module of the addedauxiliary module.

At step 2024, the vehicle 1910 is reconfigured to accommodate the addedauxiliary drive module. Step 2024 comprises updating control algorithmsin the interface modules 1934. For example, if two auxiliary drivemodules are added, the control algorithms may be updated to decrease thehorsepower produced by the original motors 1928 in response to aparticular throttle input to take into account the additional horsepowerprovided by the added electric motors 1928. Alternatively, if one of theelectric motors 1928 fails or is otherwise rendered inoperable, then theupdating compensates for less than all drive wheels being driven bycausing the remaining electric motors to be controlled to provideadditional horsepower. This gives the vehicle 1910 different modes ofoperation, for example, a first mode of operation in which the electricmotors are controlled such that all of the plurality of drive wheels aredriven, and a second mode of operation in which the electric motors arecontrolled such that less than all of the plurality of drive wheels aredriven.

At step 2026, a confirmation is sent to the operator of the vehicle 1910via a display of the operator interface 1973 to confirm that the vehiclehas been reconfigured. It may also be desirable to transmit thisinformation to other systems. For example, one of the interface modules1934 may be provided with a wireless modem, and the change inconfiguration information may be transmitted wireless to an off-boardcomputer using a radio frequency (RF) communication link. Indeed, any ofthe information stored in any of the interface modules or any of theother vehicle computers (e.g., engine control system, transmissioncontrol system, and so on) may be transmitted to an off-board computersystem in this manner to allow off-board vehicle monitoring and/oroff-board vehicle troubleshooting. The transfer of information may occurthrough a direct modem link with the off-board vehicle computer orthrough an Internet connection.

Thus, the vehicle 1910 has a modular construction, with the principalpower unit 1916, the power storage unit 1922, the energy dissipationdevice 1932, the auxiliary drive modules 1953, other drive modules 1984and 1986, and so on, being provided as modules that can be easily addedto or removed from the vehicle. Any number of such modules can be addedand is limited only by the extent to which suitable locations whichconnections to the communication network and AC bus assembly 1942 existon the vehicle 1910. Once such a device is added, the control system isautomatically reconfigured by the interface modules 1934.

FIG. 25 illustrates the wheels 1914 being driven directly by an electricmotor 1928 through an appropriate wheel-end reduction assembly 1982 ifnecessary. Referring now to FIGS. 31A-31B, a wheel-end reductionassembly 1982 can also couple the wheels 1914 to a differential assembly1978 via drive shafts. A plurality of wheel-end reduction assemblies1982 can couple the wheels 1914 to their respective electric motors1928. Another embodiment of the vehicle 1910 includes a differentialassembly 1978 coupled to the electric motor 1928 for driving at leasttwo wheels 1914 as shown in FIG. 27. Additional differential assemblies1978, such as three assemblies 1978, with each differential assemblycoupled to an electric motor 1928 for driving at least two wheels, canalso be configured in the vehicle 1910.

Referring now to FIG. 33, a method of transferring data indicative of anelectric traction vehicle 1910 to potential customers over the Internet1992 includes obtaining information on an electric traction vehicle 1910including dates, prices, shipping times, shipping locations, generalshipping data, module type, inventory, specification information,graphics, source data, trademarks, certification marks and combinationsthereof. The method further includes entering the information on to aterminal 1990 that is operationally connected to an Internet server.Terminal 1990 may be microprocessor, a computer, or other conventionallyknown device capable of operationally connecting to a conventionallyknown Internet server. The method further includes transmitting to theinformation from terminal 1990 to the Internet server that isoperationally connected to Internet 1992. Information be transmitted tothe internet from the interface modules 1934 and may include any of theinformation stored in the interface modules 1934 or any other vehiclecomputer, as previously noted. The method allows manufacturers 1994,distributors 1996, retailers 1997 and customers 1998, throughout the useof terminals 1990, to transmit information, regarding the electrictraction vehicle 1910 and the potential sale of the electric tractionvehicle 1910 to customers, to one another individually, collectively orby any combination thereof.

Thus, there is provided an electric traction vehicle of modular designwith the modules interconnected by an AC bus assembly and a data busnetwork. Other embodiments using other types of vehicles are possible.For example, an electric traction vehicle using a modular componentdesign can be utilized as a fire truck for use at an airport or one thatcan negotiate severe off-road terrain. The vehicle can also be used in amilitary configuration with the ability to negotiate extreme side slopesand negotiate extreme maneuvers at high speeds. The modular aspect ofthe vehicle architecture will allow for optimum placement of componentsto maximize performance with regard to center of gravity which willfacilitate its operational capabilities.

Throughout the specification, numerous advantages of preferredembodiments have been identified. It will be understood of course thatit is possible to employ the teachings herein so as to withoutnecessarily achieving the same advantages. Additionally, although manyfeatures have been described in the context of a vehicle control systemcomprising multiple modules connected by a network, it will beappreciated that such features could also be implemented in the contextof other hardware configurations. Further, although various figuresdepict a series of steps which are performed sequentially, the stepsshown in such figures generally need not be performed in any particularorder. For example, in practice, modular programming techniques are usedand therefore some of the steps may be performed essentiallysimultaneously. Additionally, some steps shown may be performedrepetitively with particular ones of the steps being performed morefrequently than others. Alternatively, it may be desirable in somesituations to perform steps in a different order than shown.

Many other changes and modifications may be made to the presentinvention without departing from the spirit thereof.

1. An electric traction vehicle comprising: a vehicle platform; aplurality of drive wheels coupled to the vehicle platform; a pluralityof electric motors coupled to respective ones of the plurality of drivewheels, the plurality of electric motors being used to drive theplurality of drive wheels; an electrical connector which is used toallow an electrical power-consuming system off-board the vehicle to beconnected to the vehicle and draw electrical power from the vehicle; anda power source coupled to the vehicle platform, the power source beingused to provide electrical power to the plurality of electric motors andthe electrical connector; wherein the vehicle is capable of providing atleast about 250 kilowatts of power to the off-board power-consumingsystem.